A PROCESS FOR THE PRODUCTION OF A COPPER SILICATE BY PRECIPITATION OF THE SILICATE FROM A REACTION MEDIUM CONSISTING ESSENTIALLY OF AN AQUEOUS SOLUTION OF AN ALKALI SILICATE AND A COPPER SALT, WHEREIN THE IMPROVEMENT COMPRISES PRECIPITATING THE COPPER SILICATE FROM THE SOLUTION AT AN ELECATED TEMPERATURE. THE COPPER SILICATES ARE USEFUL AS ADDITIVES TO COATINGS SUCH AS PAINTS, AND ESPECIALLY AS ANTI-FOULING AGENTS IN COATNGS FOR SHIPS.