An attempt has been made to analyze water addition in various forms to the operating medium of an LPGfueled engine. The advantages of adding water to the operating medium of an engine has been described, both for spark and compression ignition engines powered with LPG fuel, including the impact on theoperational parameters and pollutant emission. It is estimated that the addition of water to the operatingmedium has a beneficial effect on the thermal efficiency of circulation, at the same time contributingto the reduction of carbon monoxide, hydrocarbons and nitrogen oxides emission. The methodology of empirical research on spark ignited engine fueled with LPG with water addition has been presented: testing was carried out under conditions simulating traction engine usage – under the NEDC approval drive test, consisting of an Urban Driving Cycle – UDC and an Extra Urban Driving Cycle – EUDC. The characteristics of the fuel used in the test has been described, including its composition and selected physical and chemical properties. The results of empirical research have been presented, i.e. the fuel consumptionand pollutant emission. It was found that the addition of water has an effect on reducing the operational fuel consumption  and emission of carbon monoxide, hydrocarbons, nitrogen oxides and carbon dioxide under engine operating conditions corresponding both to urban and extra-urban driving conditions.