Interesting structural influence of different types of non-ionic micelles (Tween-40, Tween-80, Brij-30 and Brij-78) on the excited state proton transfer photophysics of 2-hydroxy 1-naphthaldehyde has been investigated. Anion band formation in the excited state is favored in Brij micelles, similar to aqueous environment due to hydrogen bonding ability of OH group in Brij but the same is hindered in Tween micelles. Quantum chemical calculations predicted, with free energy and enthalpy values, two possible anionic conformers (cis and trans). One of the two anionic conformers is favored in Brij 30 and addition of base seems to lower the barrier for other conformer to appear. (c) 2007 Elsevier B.V. All rights reserved.