Palladium nanoparticles electrolytic deposited onto preformed electrodes coated with polymer film was used as cathode for the electrocatalytic hydrodechlorination of dichlorophenol in aqueous solution. The surface of the electrode substrates was coated with a polypyrrole (PPY) film electropolymerized via potentiostatic method. The FT-IR results indicated that the peaks at 1550, 1190 and 960 cm(-1) were ascribed to the characteristic bands of PPYs. SEM images performed that the Pd nano-particles were uniformly dispersed on the composite electrode after modification with PPYs. Moreover, the nucleation and growth of PPY in NaClO4 was much faster than that of others from the chronoamperometry analysis. XRD and XPS results indicated that Pd existed mainly as Pd-0. TEM results showed that Pd particles were well dispersed with an average diameter of 10 nm. The effects of the dopant ions, applied potential, temperature, and reaction time of potentiostatic electropolymerization on the composite electrode for the electrochemical hydrodechlorination of 2,4-dichlorophenol (2,4-DCP) were examined. Under optimal conditions, a 90.9% removal rate for 2,4-DCP could be achieved with the use of the Pd/PPY(PTS)/Ni composite electrode. The process of 2,4-DCP dechlorination was investigated. (c) 2013 Published by Elsevier B.V.