Preheat the oven to 350 degrees F. (175 degrees C).
In a small bowl, stir together the orange juice, onion soup mix, soy sauce, and garlic powder; Set aside. Rinse chicken, and pat dry. Place chicken thighs into a 9x13 inch glass baking dish. Pour the orange juice mixture over.
Bake, uncovered, for 1 hour and 30 minutes in the preheated oven, basting every half hour. If using boneless chicken, reduce cooking time to 1 hour.