The hydrogen-bonding properties of primary, secondary, and tertiary butyl alcohols both as proton donors and as proton acceptors were studied with crotonaldehyde, cyclohexanone, and α-naphthol. The equilibrium constants were estimated from the n → π* blue shift and the π → π* red shift and optical density measurements. The results show that the proton-donating power of the alcohols decreases in the order primary > secondary > tertiary while the proton-accepting power of the alcohols decreases in the reverse order. A method has been suggested to account for the association of the alcohols in the estimation of the equilibrium constant.