The basic electrochemical behaviour of powder layer/SPE membrane composite electrodes was investigated through the redox process of ferrocene by voltammetry. The electrochemical reaction occurs at the interface between the powder layer and the SPE membrane. This kind of composite electrode that separates the diffusion of reactant from the process of ionic transport can be considered as a special planar electrode. After impregnation of the powder layer with Nafion solution, the composite electrode shows thin layer electrochemical behaviour. The main merits of this type of electrode are as follows. (1) The electrochemical kinetics of reactions involving gases or electroactive compounds slightly soluble in aqueous solution can be studied without adding supporting electrolyte. (2) The electrochemical behaviour of various powder layer/SPE membrane interface can easily be investigated without the limitations of traditional preparation methods. In addition, this technique can also be applied to electroanalytical chemistry.