In the paper, analysis of results of the experimental investigation on the influence of the moisture content in treated gaseous mixture on CO2 separation process, considering CO2/N-2 mixture separation, is presented. The paper focuses on identification of the influence and introductory analysis of selected operational parameters of the membrane on carbon dioxide separation parameters, considering CO2/N-2 mixture, humidified in the range of 0%-100% in relative humidity. During the experimental research, the UMS A2 membrane by UBE was used. The membrane selection was supported with former investigations, performed with dry gases usage. The main aim of the investigation was to verify the influence of gas humidification on CO2 separation parameters. The research concerned actions focusing on the determination of membranes' operational parameters and their characteristics under conditions of moisture presence in exhaust gases, considering CO2 separation. That mixture simulated maximal CO2 content, which might occur in exhaust gases of power production processes, especially in the case of natural gas and hard coal combustion. In the paper, characteristics and results of the comparative analysis of CO2 separation from CO2/N-2 mixture referring to dry and humidified gases are presented. Based on the research performed, humidification of gas unfavorably affects operational parameters of CO2 separation process from CO2/N-2 gas mixture.