It is well known that CO2 has a negative effect on the catalyst of the fuel cell causing inhibition in presence of H2-CO2 mixture. According to literature, CO formation is the responsible of catalyst inhibition. Since an electrochemical hydrogen compressor (EHC) has a working principle similar to a fuel cell, the presence of CO2 can also be detrimental for the behavior of the compressor. In this work, the effect of CO2 in binary H2-CO2 mixtures on the performance of an EHC has been investigated in detail. Both Reverse Water Gas Shift (RWGS) and electrochemical reduction of CO2 may occur on the catalyst of an EHC. The main aim of the manuscript is to show RWGS is the most probable cause of catalyst inhibition. For a better understanding of the parameters involved in the catalyst inhibition in presence of a H2-CO2 mixture, different working conditions, viz. voltage and H2 concentration, are applied to the compressor. These experiments show a faster catalyst inhibition for lower H2 concentrations and lower voltages supplied. The temperature also plays an important role on the performance of the compressor. Indeed, since the RWGS is an endothermic reaction, the pollution of the catalyst is faster at higher temperatures. Recovery methods are also evaluated, and it was observed that air bleeding is most convenient because of its effectivity and recovery rate.