In 12x8-inch (2-quart) baking dish or large resealable plastic bag, combine all marinade ingredients; blend well. Add chicken; turn to coat. Cover dish or seal bag; refrigerate at least 1 hour, turning chicken once.
Heat grill. Drain chicken, reserving marinade. Alternately thread chicken and grapes onto five 12-inch metal skewers.
When ready to grill, oil grill rack. Place kabobs on gas grill over medium heat or on charcoal grill 4 to 6 inches from medium coals. Cook 10 to 15 minutes, or until chicken is no longer pink, turning often and brushing frequently with reserved marinade. Discard any remaining marinade.