Preheat oven to 350. Combine cocoa, flour, soda and salt in a small bowl. Set aside. In a large bowl, beat butter, sugar, brown sugar and vanilla until creamy. Add eggs one at a time beating well after each. Gradually add flour mixture. Stir in chips. Drop by rounded tablespoonfuls onto ungreased cookie sheets. Bake 9-10 minutes until edges are lightly browned. Let stand 2 minutes before removing from cookie sheets, cool completely. ----