In a medium bowl, mix together the soy sauce and mayonnaise. Add the chicken, and turn to coat. Cover, and marinate for 30 minutes.
Preheat a grill for medium heat. When the grill is hot, lightly brush the grate with oil.
Place the chicken onto the grill with a thick coating of the marinade. Discard remaining marinade. Cook for about 10 minutes per side, or until chicken is firm and juices run clear.
