The deposition of palladium as microparticles on electrogenerated polyaniline (PAni) films accomplished by metal electroless precipitation or by electrodeposition has been used to prepare stable polymer-modified electrode systems. Its general morphology, metal particles size and distribution were obtained by AFM analysis. The PAni/Pd microparticles electrodes have been evaluated for their catalytic activity towards hydrogenation reactions upon organic compounds reduction using 4-nitro-benzaldehyde. Studies on rotating ring-disk electrodes have shown that relatively low Pd loadings are required to obtain effective electrocatalytic activity, provided a good metal particles dispersion of about 100 nm diameter is observed.