International Maritime Organization
The United Nations specialized agency for shipping safety, security and pollution prevention, based in London with 176 member states. Its conventions govern ships worldwide — and its net-zero climate framework stalled in 2025.
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- Established
- 1948
- Location
- London, United Kingdom
- Country
- United Kingdom
- Identity
- The United Nations specialized agency responsible for measures to improve the safety and security of international shipping and to prevent pollution from ships, also involved in legal matters and the facilitation of international maritime traffic.
- Membership
- 176 Member States. Sixty-six intergovernmental organizations hold observer status with the IMO, and 85 international non-governmental organizations hold consultative status.
- Founding
- Convention adopted at Geneva on 6 March 1948; entered into force on 17 March 1958; first session held in London in January 1959; became a UN specialized agency in 1959; renamed from IMCO to IMO in 1982.
- Governance
- Assembly of all member states meets every two years; a 40-member Council elected by the Assembly acts as executive organ; five committees (Maritime Safety, Marine Environment Protection, Legal, Technical Cooperation, Facilitation); Secretariat of around 300 international staff in London.
- Leadership
- Secretary-General Arsenio Dominguez of Panama, term began 1 January 2024; Secretaries-General serve a maximum of two four-year terms. Predecessor Kitack Lim of the Republic of Korea served 2016-2023.
- Headquarters
- 4 Albert Embankment, London, United Kingdom.
- Key conventions
- International Convention for the Safety of Life at Sea (SOLAS), 1974; International Convention for the Prevention of Pollution from Ships (MARPOL 73/78); INF Code (mandatory January 2001); IMDG and ISM Codes; oil-pollution liability and compensation conventions.
- Climate
- 2023 GHG Strategy aims for net-zero emissions from international shipping by or around 2050. The Net-Zero Framework was approved in draft in April 2025; formal adoption was postponed for a year in October 2025 by 57 votes to 49, with a decision meeting due by early November 2026.
Overview
The International Maritime Organization (IMO) is the United Nations specialized agency that sets the global rules for international shipping — covering maritime safety, security, and the prevention of pollution from ships. Headquartered in London, United Kingdom, it has 176 member states and works through an Assembly of all members, a 40-member Council, and five committees. Its conventions, above all SOLAS and MARPOL, govern how ships are built and operated — and its emissions-pricing attempt stalled in 2025 (Devex).
The organization began in 1948 as the Inter-Governmental Maritime Consultative Organization (IMCO), took a decade to come into existence, and took its present name in 1982 (United Nations Dag Hammarskjold Library). Its Secretary-General is Arsenio Dominguez of Panama, whose term began on 1 January 2024, succeeding Kitack Lim of the Republic of Korea (Devex). The IMO’s remit today spans safety, environmental protection, legal matters, technical cooperation, maritime security, and the efficiency of shipping (Max Planck Encyclopedia of European Private Law).
From IMCO to IMO: a decade to exist, then a new name
An international conference in Geneva adopted the Convention establishing the organization on 6 March 1948, but the new body took a decade to come into existence. The delay came from a dispute over its proper role: the Convention’s economic objectives — removing discriminatory action and unfair restrictive practices in shipping — were rejected by the main shipping nations, and entry into force waited until states tacitly understood those objectives would not be pursued. The Convention entered into force on 17 March 1958, the organization held its first session in London in January 1959, and that same year it became a specialized agency of the United Nations. It began life as the Inter-Governmental Maritime Consultative Organization (IMCO) and took its present name, the International Maritime Organization, in 1982. Its first Secretary-General was Ove Nielsen of Denmark, who served from 1959 to 1961 (Devex; Max Planck Encyclopedia of European Private Law; United Nations Dag Hammarskjold Library).
Later Secretaries-General include Chandrika Prasad Srivastava of India (1974–1989), Efthimios Mitropoulos of Greece (2004–2011), Koji Sekimizu of Japan (2012–2015), and Kitack Lim of the Republic of Korea (2016–2023) (United Nations Dag Hammarskjold Library).
How the IMO makes rules the world fleet must follow
The IMO’s Assembly, made up of all member states, meets every two years and approves the work programme and budget. Between sessions, a 40-member Council elected by the Assembly acts as the executive organ, supervising the organization’s work. The detailed rulemaking happens in five committees — Maritime Safety, Marine Environment Protection, Legal, Technical Cooperation, and Facilitation — supported by a Secretariat of around 300 international staff in London led by a Secretary-General appointed for a maximum of two four-year terms. Conventions enter into force once states representing a set share of the world fleet have ratified them. Amendments to SOLAS move faster under “tacit acceptance”: they are deemed accepted after two years unless more than a third of contracting governments, or governments holding at least half the world’s merchant tonnage, object — and they enter into force six months later (United Nations Dag Hammarskjold Library; Devex; Max Planck Encyclopedia of European Private Law; SOLAS Article VIII).
The IMO’s authority is written into other treaties: whenever the United Nations Convention on the Law of the Sea (UNCLOS) refers to the “competent international organization,” the reference is to the IMO (Max Planck Encyclopedia of European Private Law). Sixty-six intergovernmental organizations hold observer status with the IMO, and 85 international non-governmental organizations hold consultative status (Devex).
The conventions that run world shipping
The IMO’s best-known instruments are the safety and pollution conventions: the International Convention for the Safety of Life at Sea (SOLAS), 1974, and the International Convention for the Prevention of Pollution from Ships (MARPOL 73/78). Around them sits a web of codes and liability treaties — some binding, some guidance — covering dangerous goods, ship management, oil-pollution compensation, and the removal of wrecks. By 2012 the organization had produced about 50 conventions and more than 800 codes and recommendations. One specialist code shows how far the web reaches: the INF Code, adopted voluntarily in 1993 and mandatory from January 2001, sets ship-design rules for carrying irradiated nuclear fuel, plutonium, and high-level radioactive waste, complementing the package-safety regulations of the International Atomic Energy Agency. Its ships are sorted into three classes, INF 1, INF 2, and INF 3, by the aggregate radioactivity they may carry (Max Planck Encyclopedia of European Private Law; World Nuclear Transport Institute). The World Nuclear Transport Institute’s fact sheet for purpose-built vessels sets out the INF Code’s ship-design requirements, including a 55°C cap on average cargo-space temperature (World Nuclear Transport Institute).
| Convention or code | Year | What it covers |
|---|---|---|
| SOLAS | 1974, as amended | Safety of life at sea — ship construction, equipment, and operation |
| MARPOL 73/78 | 1973 / 1978 | Prevention of pollution from ships, from operational and accidental causes |
| INF Code | 1993 voluntary; mandatory January 2001 | Design and operation of ships carrying irradiated nuclear fuel, plutonium, and high-level radioactive waste |
| IMDG Code | Mandatory 2004 | Carriage of dangerous goods by sea |
| ISM Code | Mandatory 1998 | Safe operation of ships and pollution prevention management |
| CLC + IOPC Funds | CLC 1969 (in force 1975); Funds 1971 / 1992 | Strict liability of shipowners for oil-pollution damage, plus a compensation fund for damage the liability regime does not cover |
| LLMC | 1976 (1996 Protocol) | Limitation of shipowners’ liability for loss of life, personal injury, and property damage |
| Bunker Oil Convention | 2001 (in force November 2008) | Strict liability for bunker-oil pollution damage |
| Nairobi Wreck Removal Convention | 2007 | Strict liability for locating, marking, and removing wrecks |
(Max Planck Encyclopedia of European Private Law; World Nuclear Transport Institute)
The net-zero fight: a framework approved, then stalled
In 2023 the IMO adopted a revised greenhouse-gas strategy aiming for net-zero emissions from international shipping by or around 2050, with interim checkpoints for 2030 and 2040. In April 2025, at the 83rd session of the Marine Environment Protection Committee, member states approved draft rules — a new Chapter 5 of MARPOL Annex VI — that would require ships over 5,000 gross tonnage, responsible for about 85 percent of shipping’s carbon dioxide, to cut their fuel’s greenhouse-gas intensity over time, buying remedial units when they overshoot and earning surplus units when they beat the standard, with an IMO Net-Zero Fund collecting the payments. But formal adoption, scheduled for October 2025, was postponed for a year by 57 votes to 49 at an extraordinary committee session after opposition led by the United States — and in September 2026, President Donald Trump used a United Nations General Assembly speech to denounce the framework as a global carbon tax (SAFETY4SEA; Cruise & Ferry).
The delay is already biting. Singapore’s marine biofuel sales fell 47% in January–September 2026 compared with the same period in 2025 (Reuters) — a sign that regulatory uncertainty is chilling investment in cleaner fuels, since shipowners will not pay for greener fuel without a clear IMO decision. “I don’t expect the biofuel demand to increase so much until we have an IMO decision,” Jens Maul Jorgensen of dry bulk shipowner Oldendorff Carriers told Reuters (Reuters). Meanwhile regional rules are filling the gap: international shipping is already subject to the EU Emissions Trading System, and FuelEU Maritime has introduced greenhouse-gas intensity requirements for ships calling at EU ports (SAFETY4SEA). IMO member nations were set to meet by early November 2026 on formal adoption (Reuters).
Who does what around the IMO
| Body | Remit | Relationship to the IMO |
|---|---|---|
| International Labour Organization (ILO) | Maritime labour law, labour standards, and social protection in shipping | Parallel UN specialized agency; the IMO leaves labour questions to the ILO |
| International Telecommunication Union (ITU) | Maritime satellite navigation and telecommunications | Parallel UN specialized agency covering the telecom side of shipping |
| UNESCO | Protection of underwater cultural heritage | Its 2001 convention operates alongside IMO instruments |
| International Atomic Energy Agency (IAEA) | Safety of radioactive-material transport, based on safety ensured primarily by the package | The IMO’s INF Code complements IAEA regulations with ship-specific requirements |
| European Union (EU) | Port-state-control directives; EU Emissions Trading System and FuelEU Maritime for ships calling at EU ports | Regional rules developing alongside — and sometimes ahead of — the IMO’s global framework |
| UNCLOS | The law of the sea | Refers to the IMO as the “competent international organization” |
(Max Planck Encyclopedia of European Private Law; World Nuclear Transport Institute; SAFETY4SEA)
FAQ
What does the IMO do? The IMO develops and maintains the global regulatory framework for international shipping. Its remit covers maritime safety, environmental protection, legal matters, technical cooperation, maritime security, and shipping efficiency. It drafts conventions such as SOLAS and MARPOL, which member states bring into force by ratifying them (Max Planck Encyclopedia of European Private Law).
When was the IMO founded? The founding Convention was adopted in Geneva on 6 March 1948, but the organization only came into existence when the Convention entered into force on 17 March 1958. It held its first session in January 1959, became a UN specialized agency that year, and changed its name from IMCO to IMO in 1982 (United Nations Dag Hammarskjold Library).
How many members does the IMO have? The IMO currently has 176 member states. Its Assembly includes all member states and meets every two years, while a 40-member Council elected by the Assembly supervises the organization between sessions. Sixty-six intergovernmental organizations hold observer status and 85 NGOs hold consultative status (Devex).
How do IMO rules become binding? Conventions enter into force after states holding a set fleet share ratify them. SOLAS amendments use tacit acceptance: they are deemed accepted after two years unless over a third of contracting governments, or governments holding at least half the world’s merchant tonnage, object — effective six months later (Max Planck Encyclopedia of European Private Law; SOLAS Article VIII).
What happened to the IMO’s net-zero framework? Member states approved the draft Net-Zero Framework in April 2025, but postponed formal adoption for a year in October 2025 by 57 votes to 49 after United States opposition. As of October 2026, member nations were set to meet by early November on formal adoption, while the delay had already cooled demand for lower-carbon marine fuels (SAFETY4SEA; Reuters).
What this profile does not claim
This profile does not state the role of the STCW seafarer-training convention, which was not verified in a full-read source during this pass. It does not cover any meteorological organization that historically shared the IMO acronym — it covers only the London-based maritime agency. It does not predict the outcome of the IMO adoption meeting due by early November 2026. It does not state the IMO’s budget or exact current staffing beyond Devex’s “around 300.” It does not assess how well member states enforce IMO instruments in practice, and it does not present the 2012 figures in the Max-EuP article (169 members, a 32-member Council) as current.
Timeline
- 1948
- An international conference in Geneva adopts the Convention establishing the organization on 6 March, under the name Inter-Governmental Maritime Consultative Organization (IMCO).
- 1958
- The Convention enters into force on 17 March, after a ten-year delay caused by disagreement over whether the organization should pursue economic as well as technical objectives.
- 1959
- The organization holds its first session in London in January and becomes a specialized agency of the United Nations. Ove Nielsen of Denmark serves as its first Secretary-General, 1959-1961.
- 1982
- The organization is renamed from IMCO to the International Maritime Organization.
- 1993
- The IMO introduces the INF Code as a voluntary code for ships carrying irradiated nuclear fuel, plutonium and high-level radioactive waste, complementing the IAEA's transport regulations.
- 2001
- The INF Code becomes mandatory in January.
- 2023
- The IMO adopts a revised GHG Strategy aiming for net-zero greenhouse gas emissions from international shipping by or around 2050, with interim checkpoints for 2030 and 2040.
- 2025-04
- At MEPC 83 (7-11 April), member states approve draft Net-Zero Framework rules as a new Chapter 5 of MARPOL Annex VI, covering ships over 5,000 gross tonnage.
- 2025-10
- An extraordinary MEPC session postpones formal adoption of the framework for one year, by 57 votes to 49, after opposition led by the United States.
- 2026-09
- US President Donald Trump denounces the framework in a 22 September speech to the UN General Assembly, calling it a first-ever global carbon tax and claiming it could raise shipping costs by 10-20%.
- 2026-10
- Reuters reports IMO member nations are set to meet by early November on formal adoption, while Singapore marine biofuel sales fell 47% in January-September 2026 as the rules hung in the balance.
What we could not verify
These claims came up in research and could not be confirmed. They are recorded here rather than published as fact or quietly dropped. If you hold a source that settles one, please tell us.
- The role of the STCW seafarer-training convention was not verified in a full-read source during this pass and is not stated.
- A separate meteorological organization historically shared the IMO acronym; its history was not verified in a full-read source and is not stated — this profile covers only the London-based maritime agency.
- The outcome of the IMO adoption meeting due by early November 2026 was not yet known at writing and is not stated.
- The IMO's budget and exact current staffing beyond Devex's "around 300" were not verified and are not stated.
- Enforcement and compliance with IMO instruments in practice were not assessed in a full-read source and are not stated.
Sources
8 sources (3 tier 1, 5 tier 2), each opened and read against the claim it supports. Every source is independent of the subject; no first-party material is cited. See the source policy.
Built from sources fetched and read in full: UN Dag Hammarskjold Library documentation (tier1) for founding, structure and the Secretary-General list; Devex (tier2) for membership, structure and leadership; Reuters (tier1) for the October 2026 state of the net-zero talks; SAFETY4SEA and Cruise & Ferry (tier2) for the framework's approval, postponement and contents; the Max Planck Encyclopedia of European Private Law (tier1, 2012) for history, purposes and the convention system — its first 132 of 144 lines were read and its 2012 membership/Council figures are treated as historical, not current; the World Nuclear Transport Institute (tier2) for the INF Code; and the reproduced SOLAS Article VIII amendment text (tier2) for the tacit-acceptance procedure. Three further pages (the tail of the Max-EuP article, a WMO history page, and the IMO's own INF Code page) could not be fetched because of a rate limit; none is cited.
- Supports: IMCO established 1948, specialized agency 1959, renamed IMO 1982; Convention concluded Geneva 1948, in force 1958; Assembly of all Member States meeting every two years; Council of 40 members; full Secretary-General list (Ove Nielsen 1959-1961 through Arsenio Dominguez 2024-). Open original source
- Supports: IMO member nations set to meet by early November on formal adoption of the net-zero framework after last year's vote to delay; Singapore marine biofuel sales about 603,000 tons January-September, down 47% from 2025; shipowner and fuel-supplier quotes on regulatory uncertainty; EU FuelEU Maritime regulation for ships over 5,000 gross tonnage calling at EU ports. Open original source
- Supports: Convention of 6 March 1948, in force 17 March 1958, first session January 1959, IMCO renamed IMO 1982, seat London; ten-year delay because economic objectives were rejected by main shipping nations; purposes (cooperation, highest practicable standards, pollution prevention since 1982, unlawful acts since 1985); about 50 conventions and more than 800 codes and recommendations by 2012; SOLAS 1974 and MARPOL 73/78; UNCLOS references to IMO as "competent international organization"; CLC, IOPC Funds, LLMC, Salvage, HNS, Bunker and Nairobi conventions; IMDG Code mandatory 2004, ISM Code mandatory 1998; conventions enter into force after ratification thresholds tied to world fleet share; relations with CMI, UNCITRAL, UNCTAD, ILO, ITU, UNESCO and the EU. First 132 of 144 lines read; 2012 membership (169) and Council (32) figures not used as current. Open original source
- Supports: UN specialized agency for safety/security of shipping and pollution prevention; Convention adopted Geneva 6 March 1948, first meeting January 1959; 176 Member States, 66 IGO observers, 85 NGOs in consultative status; Secretariat around 300 staff; Secretary-General maximum two four-year terms; Arsenio Dominguez of Panama, term began 1 January 2024; Assembly approves work programme and budget; Council elected for two-year terms as executive organ; five committees; headquarters 4 Albert Embankment, London. Open original source
- Supports: Trump UNGA speech 22 September 2026 and his 10-20% shipping-cost claim; framework approved in draft at MEPC 83 April 2025 (mandatory fuel standard plus economic mechanism); ships over 5,000 GT, about 85% of CO2 from international shipping; remedial and surplus units; IMO Net-Zero Fund; adoption postponed one year by 57 votes to 49 at an extraordinary MEPC session after US opposition; 2023 GHG Strategy net-zero by or around 2050 with 2030/2040 interim targets; EU ETS and FuelEU Maritime context. Open original source
- Supports: MEPC 83, 7-11 April 2025 at IMO headquarters, London; measures as new Chapter 5 of MARPOL Annex VI; mandatory for ocean-going ships over 5,000gt, about 85% of CO2 from international shipping; greenhouse gas fuel intensity reductions, remedial units, IMO Net-Zero Fund uses; framework described as first legally binding framework combining mandatory emissions limits and GHG pricing; Dominguez quote on adoption. Open original source
- Supports: IAEA Regulations for the Safe Transport of Radioactive Material first published 1961, safety ensured primarily by the package; IMO introduced the INF Code in 1993 as a voluntary code complementing the IAEA Regulations, addressing damage stability, fire protection and structural resistance; INF Code mandatory January 2001; INF 1/2/3 classes by aggregate radioactivity (INF 1 under 4,000 TBq; INF 2 under 2 x 10^6 TBq, plutonium under 2 x 10^5 TBq; INF 3 no restriction); domestic legislation from IMO conventions including SOLAS, MARPOL and the IMDG Code; cargo-space temperature cap 55C. Open original source
- Supports: SOLAS amendment procedure: amendments adopted by two-thirds majority of Contracting Governments in the expanded Maritime Safety Committee; annex amendments deemed accepted after two years (or a period of not less than one year); deemed not accepted if more than one-third of Contracting Governments, or governments whose fleets are at least 50% of world gross tonnage, object; entry into force six months after deemed acceptance. Open original source
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