An electrochemical reactor, with a membrane-electrode-assembly technology, has been developed for the electrochemical reduction of CO2 in gas phase. The reactor was carefully designed to prevent the strong corrosion by the high overpotentials required for addressing CO2 reduction. In addition, electrodes based on Fe and Pt supported on Vulcan XC-72R (the commercial carbon black often used for electrochemical applications) were used as cathode. These electrodes favor the CO2 confinement in the nanoporous structure of the carbon support, resulting in higher pressures at the electrocatalytic surface, and consequently, enhancing the performance. The behavior of the electrodes for CO2 reduction was studied in both acid media (0.5 M H2SO4) and in gas phase using the designed reactor in order to establish a correlation of the results. A higher current density was developed for the Pt based electrode due to a significant formation of H-2 by the water reduction, whereas the CO2 conversion could be favored on the Fe electrode, in both acid media and gas phase. (C) 2016 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.