In a large bowl, mix the olive oil, soy sauce, lemon juice, liquid smoke, mustard, pepper, and garlic powder. Place chicken in the bowl, and coat with the marinade. Cover, and allow chicken to marinate a maximum of 4 hours in the refrigerator.
Preheat the grill for high heat.
Oil grill grate. Discard marinade, and place chicken on grate. Cook 6 to 8 minutes on each side, until juices run clear.