Preheat oven to 400 degrees F. Pour rice and water into a 13" x 9" foiled lined pan. Sprinkle onion soup evenly over rice. Press onion soup very lightly into rice and water until it's just barely moistened.
Rinse chicken and arrange in pan on top of rice/water/soup in a single layer. Cover everything with cream of mushroom soup, concentrating first on covering the chicken and then rice (with any remaining soup).
Place in preheated oven for 1 hour. Chicken is done when rice begins to dry around edges and chicken is brown. Remove from oven and let stand 10 minutes before serving.