Cut each chicken breast, pineapple, peppers and onion into approximately 24 one inch thick pieces.
Combine chicken, pineapple juice, garlic, soy sauce and oil in a large bowl (nonmetallic).
Marinate in refrigerator for at least 1 hour and up to 24 hours.
Preheat grill and lightly coat vegetables with cooking spray.
Thread 2 pieces of pepper, pineapple, chicken and onion onto each of 8 skewers.
Grill over medium heat until chicken is completely cooked, approximately 8 to 10 minutes, turning kabobs as necessary.