A gas turbine is designed by taking into account the standard ISO conditions: 15 °C, 1.013 bar and 60 % relative humidity. During summer, the air temperature increases and its density decreases. That leads to the reduction of air flow within turbine's intake and, consequently, of the power delivered by the turbo engine. Thus, a 1°C of air temperature increase means that the delivered power decreases with 0.45 - 0.9% [1]. One of the used methods for compensating the power loss is the cooling of the intake air by spraying pulverized water in the engine's intake. The post-combustion is situated downstream in relation to the turbo engine and, thus, will be influenced by its activity regarding flame stability and emissions. Usually, in order to compensate the power loss of a co-generative power group, water injection starts only if the nominal power of the engine is 50 % or more. The environment regulations are more and more restrictive and have determined researches related to the decrease of the emissions even at the starting of the co-generative group. Considering the above mentioned aspects, water injection in engine's intake, increase its power and may lead to the decrease of the NOx emissions [2]. Present paper is presenting the researches performed at INCDT COMOTI on its post combustion testing stand, regarding the impact of water injection in engine's intake at its starting. The experiments have been performed by using a TV2-117A turbo engine, modified by INCDT COMOTI's specialists to work on natural gas rather than kerosene. The methodology for emphasising the power increase and the relation between NOx emissions and burned gas temperature is described and detailed. The experimental emission data collected both at the chimney and at the residential/industrial interface allowed the charting of NOx dispersion. By analysing the dispersion charts, it was highlighted that NOx levels at the interface are way below the limits imposed by the in force regulations.