A thin metallic film electrode deposited on a porous substrate, in this case a glass frit, in which electrolyte is entrained, may:permit electrochemical effects with gas-phase reagents. Direct current sputtering is a convenient physical deposition method to prepare these electrode [1-3] and catalyst [4] materials. By using appropriate sputtering parameters (current density, voltage and time), metallic particles (Au, Pt, Pd, etc.) were deposited, forming continuous conducting films on rough, porous glass frit substrates. Supporting electrolyte was entrapped in the pores and the surface metallic films used as electrodes [5], the reagents being absorbed from the gas phase. In the present work sputtered Pr films, or Pt clusters sputtered on thin (350 nm) evaporated gold films were used as working electrodes. The morphology of these platinum films. as well as their modifications in service, were examined by-scanning electron microscopy (SEM) and by atomic force microscopy,(AFM). Various electrooxidations of gases such as CO, H-2 and methanol vapor demonstrated the electroactivity of Pt clusters as gas adsorption electrodes.