A Raman cell suitable for the study of solid/liquid/gas three-phase systems and that can work very efficiently on confocal microprobe Raman systems was introduced. The influence of the environment on the adsorption behavior of model molecule CO on Pt was investigated and different behaviors were observed in the aqueous solution compared to the gas phase. A preliminary Raman measurement on the three-phase system was performed using methanol as a testing solution. The diffusion of CO, a dissociate product of methanol, on the Pt electrode from the solution side to the gas side was observed. (C) 2003 Elsevier Science B.V. All rights reserved.