The selective styrene oxidation to benzaldehyde was studied over Cr-ZSM-5 zeolite which was selected after probed a series of transition metal cations (chromium, cobalt, iron, zinc, manganese and cupper) using hydrogen peroxide as oxidant agent. The effects of various reaction parameters such as reaction time, catalyst mass, styrene/hydrogen peroxide molar ratio, solvent nature and reaction temperature effect were evaluated over it. Using the initial rate method, a first order with respect to styrene and oxidant concentrations was determined. An apparent activation energy of 14.54 kJ/mol was obtained. (C) 2011 Elsevier B.V. All rights reserved.