Combine oil, lemon juice, pepper, Italian seasoning and garlic powder in a large resealable plastic bag. Add chicken; seal bag and turn to coat. Marinate in refrigerator a minimum of 15 minutes.
Preheat oven to 350℉.
Remove chicken from marinade; discard remaining marinade. Place chicken breasts in a single layer on baking pan.
Bake about 20 minutes, or until done (chicken is no longer pink in center). Baking time will depend on thickness of chicken.