An electrochemical codeposition method was used to prepare a Pd/MoOx/GC composite electrode that provides a surface modification with catalytic properties for dechlorination of 4-chlorophenol. This method allows the mixing of metal and oxide on a microscopic level to disperse the Pd microparticles into the molybdenum oxide on a glassy carbon, and the SEM result showed the uniform dispersion of the particles on glassy carbon (particle sizes are about 100-200 nm), X-ray photoelectron spectroscopy of the composite electrode presented a broad peak in the Mo (3d) region revealing the existence of Mo6+ species as well as lower valence states such as Mo5+, Mo4+. This composite electrode showed a better performance for electrocatalytic reductive dechlorination of 4-chlorphenol than Pd/GC. The effect of current density for dechlorination was also investigated. (C) 2003 Elsevier B.V. All rights reserved.