The electrodeposition of platinum microparticles into a 2,5-diaminobenzenesulfonic acid-modified polyaniline (SPANI) film on IrO2 electrodes and its electrosorption for methanol and sorbitol, respectively, are described. Electrodeposited platinum microparticles under constant potential are dispersed in a three-dimensional array in porous SPANI films as evidenced by Auger electron spectroscopy (AES). Characterization of the Pt/SPANI/IrO2 electrodes by SEM shows that the deposition procedure yields spherical catalyst particles. X-ray photoelectron spectroscopy (XPS) results show that there is not significant variability in the binding energy of carbon and nitrogen, respectively, on SPANI chains for different Pt loadings. I:or catalyst loading of ca. 7 mg cm(-2) deposited at -200 mV, the electrosorption coverages of sorbitol are always greater than that of methanol about 15%. In comparison to sorbitol, the readsorption of methanol on Pt catalyst site occurs significantly during electrosorption.