The issue of ecologic and economic efficiency of environmental management systems (EMSs) certified by ISO 14001 is still discussed in the literature. The percentage of certified EMS of Russian energy companies is far above those of other industries, due to the fact that electricity generation industry is one of most pollutant-intensive sectors. This study contributes to the literature by proposing a dynamic environmental DEA model with radial efficiency measure and constant return to scale to analyze the efficiency of the environmental management systems of gas-fired power plants in Russia. The suggested method for evaluating the efficiency of EMS allows one to research the following practical issues: (i) to compare the efficiency of EMS of different production divisions that use similar production technologies; (ii) to compare the maturity of EMS based on a trend of a company's ecologic efficiency; (iii) to compare ecologic efficiency of different production technologies.