'OC' was the designation of Allied convoys (together with a numerical suffix) plying the route from Melbourne to Newcastle, Australia, and as such reciprocals of the 'CO' series (June 1942/December 1943).

The first of these 149 convoys was OC.1 of 10/13 June 1942 with nine merchant vessels (3,289-ton US Admiral Halstead, 4,238-ton British Bundaleer, 2,515-ton British Cardross, 7,063-ton British City of Lyons, 2,197-ton British Coolana, 3,351-ton British Dumosa, 4,584-ton British Iron King, 2,071-ton Dutch Janssens and 9,032-ton British Madura) escorted by the US destroyer Flusser and Australian minesweeper Moresby.

The last convoy was OC.149 of 6/10 December 1943 with seven merchant vessels (3,346-ton British Corio, 3,553-ton Greek Elisavet, 3,352-ton British Iron Prince, 1,631-ton British Koonda, 3,351-ton British Mungana, 2742-ton British Talune and 2,393-ton British William McArthur) escorted by the Australian minesweepers Ballarat and Doomba, and auxiliary patrol vessel Wilcania.