Melt butter in a medium saucepan over medium-low heat. Add ketchup and next 4 ingredients (ketchup through hot sauce); bring to a boil. Partially cover, and cook until reduced to 2/3 cup (about 15 minutes), stirring often.
Place chicken on grill rack coated with cooking spray. Grill 12 minutes or until done, turning and basting with 1/3 cup sauce after 8 minutes; serve with remaining 1/3 cup sauce.