Palladium-bismuth films supported on glassy carbon substrates were prepared by cathodic electrodeposition of palladium ad subsequent adsorption of bismuth species on the electrode surface. A mechanism regarding the irreversible adorption process of bismuth species on the palladium surface, was described. The resulting active film was characterized, and in particular, the electrooxidation of some aliphatic aldehydes was investigated in moderately alkaline solutions. The bismuth adlayer increases the overall rate of the oxidative processes through a combination of a third body mechanism and a true catalyst. The oxidation currents of propionaldehyde, evaluated in cyclic voltammetry increased linearly on increasing analyte concentration up to 8 mM. Under chronoamperometric conditions at the constant applied potential of -0.2 V versus SCE, the resulting calibration plot for propionalclehyde analysis was linear over the range of 1.5-8 mM with a correlation coefficient better than 0.97. Throughout the XPS investigation Pd 3d and Bi 4f detailed regions an average chemical composition of the surface composite film of Pd96 +/-2Bi4 +/- 2 was evaluated. (c) 2006 Elsevier Ltd. All rights reserved.