Conductive and porous polythiophene (PTh) films, which are used as host matrixes for Pt and Pt-Pd nanoparticles, are synthesized electrochemically. PTh films containing nanometer-sized Pt and Pt-Pd bimetallic particles are electro synthesized on an indium doped tin oxide (ITO) plate by voltammetric cycling between -0.2 and +1.4 V (versus Ag/AgCl/3 M NaCl). The ensuing PTh electrode, modified with nanoparticles, was probed for its catalytic activity towards the electrooxidation of formic acid, an industrially important material. The modified electrode exhibits significant eletrocatalytic activity towards the oxidation of formic acid and this may be attributed to (a) the uniform dispersion of nanoparticles in the PTh film and (b) the efficacy of the nature of Pd species in Pt-Pd bimetallic systems. Monometallic (Pt) and bimetallic (Pt-Pd) nanoparticles are found to be uniformly dispersed in PTh matrixes as confirmed from analytical data using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Energy dispersive X-ray analysis (EDAX) is used to characterize the composition of metal present in the nanoparticles modified electrodes. (c) 2006 Elsevier B.V. All rights reserved.