A solid-polymer-electrolyte electrolysis cell was fabricated to oxidize anhydrous hydrogen chloride to chlorine gas at the anode. Protons transferred through the solid polymer electrolyte to the cathode, where hydrogen was evolved in an aqueous medium. Experimental results are presented in terms of short-time polarization data and steady-state results. Various temperatures and catalyst materials were studied. Current densities up to 900 mA/cm(2) were obtained. A simple model, developed to describe the system, includes components of gas-phase mass transfer, electrode reactions, and transport in the membrane.