38.0256°N -122.1161°WMococo 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.