A resonance Raman study of (2-hydroxy-5-rnetheylpheny1azo)benzene and (2-hydroxynaphthy1azo)benzene and their derivatives is presented. The characteristic modes in the azo and hydrazone forms are identified. Structures for both types of compounds in the solid state are proposed. It is shown that hydroxy substitution at the ortho position forms a hydrogen bond with the nitrogen atom of the azo group in arylazophenols. The effect of ring substitution on the characteristic modes is also discussed.