Preheat grill to medium. In small bowl stir together peanut butter, lime juice, soy sauce, garlic, curry powder, and red pepper.
Place chicken breasts on grill rack. Brush with half the peanut butter mixture. Grill for 6 minutes; turn and brush the remaining sauce. Grill 6 to 7 minutes more or until chicken is no longer pink in the middle (170°F).