38°01′32″N 122°06′58″W / 38.02556°N 122.11611°W / 38.02556; -122.11611 Mococo is a former unincorporated community, now annexed to the city of Martinez, located in Contra Costa County, East Bay region, California. It became known as Mococo following the 1905 arrival of a smelting works, operated by the Mountain Copper Company (Mo Co Co).

It lies at an elevation of 10 feet (3 m), south of the Carquinez Strait in eastern Martinez.

• U.S. Geological Survey Geographic Names Information System: Mococo, Martinez, California