In a small bowl, combine the ketchup, soy sauce, honey, ginger and garlic powder. Pour 1 cup marinade into a large resealable plastic bag; add the chicken. Seal bag and turn to coat; refrigerate for at least 4 hours or overnight. Cover and refrigerate remaining marinade for basting.
Drain chicken and discard marinade. Grill, covered, over medium heat for 5 minutes. Turn to baste with reserved marinade. Grill 5-10 minutes longer or until juices run clear, burning and basting occasionally.