The IMO's structure comprises the Assembly, the Council, the Maritime Safety Committee, the Marine Environment Protection Committee, the Legal Committee, the Technical Cooperation Committee, and the secretariat, headed by a Secretary-General.
The governing body of the IMO is the Assembly, composed of all IMO members. The Assembly determines the work program and votes on the budget to which all members contribute. It meets once every two years in regular sessions, but may also meet in extraordinary session if necessary.
Between sessions of the Assembly, the Council performs all functions of the organization except that of recommending the adoption of maritime safety regulations, a prerogative of the Maritime Safety Committee. The Council also has an important policymaking role. Drafts of international instruments and formal recommendations must be approved by the Council before they can be submitted to the Assembly.
The Council is made up of 40 members elected by the Assembly for two-year terms: ten members represent states with the largest international shipping services; ten represent states with the largest international seaborne trade; and 20 represent states, not elected under the foregoing categories, that have special interests in maritime transport or navigation and whose presence in the Council will ensure representation of the world's major geographic areas. The Council normally meets twice a year. The members of the Council elected by the 22st Assembly in 2002 for 2002–03 were: (from the first category) China, Greece, Italy, Japan, Norway, Panama, Republic of Korea, Russian Federation, United Kingdom, United States; (from the second category) Argentina, Bangladesh, Brazil, Canada, France, Germany, India, Netherlands, Spain, Sweden; and (from the last category) Australia, Bahamas, Chile, Cyprus, Denmark, Egypt, Ghana, Honduras, Indonesia, Kenya, Lebanon, Malta, Mexico, Nigeria, Philippines, Poland, Singapore, South Africa, Turkey, and Venezuela.
The Maritime Safety Committee is made up of all IMO member states. Its work is carried out mainly through nine sub-committees working in the following areas: bulk liquids and gases; carriage of dangerous goods, solid cargoes and containers; fire protection; radiocommunication and search and rescue; safety of navigation; ship design and equipment; stability and load lines and fishing vessels safety; standards of training and watch-keeping; flag state implementation.
The Marine Environment Protection Committee is responsible for all matters relating to the prevention and control of marine pollution from ships.
The Legal Committee, established in the aftermath of the Torrey Canyon disaster of 1967 to deal with the legal problems arising from that incident, is responsible for any legal matter within the scope of the IMO.
The Technical Cooperation Committee coordinates the work of the IMO in providing technical assistance in the maritime field, especially to developing countries.
The Facilitation Committee is a subsidiary body of the Council. It was established in May 1972 and deals with IMO's work in eliminating unnecessary formalities and "red tape" in international shipping.
The secretariat consists of a Secretary-General, appointed by the Council with the approval of the Assembly, and an international staff of about 300. IMO headquarters are at 4 Albert Embankment, London, England, UK, SE1, 7SR.
The Secretary-General is William A. O'Neil, of Canada, who was appointed to the position with effect of 1 January 1990. He heads a staff of approximately 300.