PREHEAT oven to 350° F.
COMBINE flour, cocoa, baking soda and salt in a small bowl. Beat butter, granulated sugar, brown sugar and vanilla extract in a large mixing bowl until creamy. Add eggs one at a time, beating well after each addition. Gradually beat in flour mixture. Stir in morsels. Drop by well-rounded teaspoon onto ungreased baking sheets.
BAKE for 8 to 10 minutes or until centers are set. Cool on baking sheets for 2 minutes; remove to wire racks to cool completely.