'Demcat' was a British air and sea search for U-boat supply ships believed to be operating in the Gulf of Aden and/or the Gulf of Oman (21/30 October 1942).

The British ships in this unsuccessful undertaking, whose main patrol effort began on 27 October, were the heavy cruiser Devonshire and light cruisers Enterprise and Mauritius of Force 'D', and these were supported by Consolidated Catalina twin-engined long-range flying boats of Air Chief Marshal Sir Philip Joubert de la Ferté's RAF Coastal Command.

The operation was undertaken in a rectangular area between the equator and latitude 06.40° N and between longitude 059.10° and 067.00° E. The four quarters of this rectangle were searched by the cruisers, which spaced 75 miles (121 km) apart and steamed in parallel while the aircraft searched ahead to spot surface contacts. Once the Catalina flying boats had reached the end of their search range, the cruisers were free to use their own aircraft to search farther.