The Convention on the International Maritime Organization was prepared and opened for signature and acceptance by the United Nations Maritime Conference convened by the Secretary-General of the United Nations pursuant to Economic and Social Council resolution 35 (IV). The Conference met at Geneva from 19 February to 6 March 1948.
As a result of the entry into force of the amendments adopted by the IMCO Assembly by its resolutions A.358 (IX) of 14 November 1975 and A.371 (X) of 9 November 1977 [rectification of resolution A.358 (IX) (see chapter XII.1(d)]], the name of the Intergovernmental Maritime Consultative Organization (IMCO) has been changed to "International Maritime Organization (IMO)" and the title of the Convention modified accordingly.
From: United Nations Treaty Collection [Online] Chapter XII, Navigation
The UN and the Sea