A new reactive separation process is presented and analyzed which is based on simultaneous, dispersionless gas-liquid absorption and electrochemical reaction in the pore structure of electrically conductive membranes. As a model process of technical and environmental relevance, the electrochemical absorption of chlorine waste gases in hydrochloric acid is studied, both experimentally and theoretically. The membranes were manufactured from porous carbon black particles by rolling agglomeration. The reaction mechanisms and mass transport phenomena within these membranes were investigated in a novel cyclone flow reactor. With this membrane reactor, a series of experiments was carried out under control of membrane electrode potential using chlorine-nitrogen gas mixtures (1000 ppm Cl-2). A model-based analysis of experimental data reveals the electrochemical reaction microkinetics to follow the Volmer-Heyrovsky mechanism. Mass transport was found to be dominated by Knudsen diffusion in the membrane micropores.