Gasoline-powered internal combustion engines emit compounds of carbon, nitrogen, sulfur and lead, and hydrocarbons. The article presents the investigation subject related to amount of harmful chemicals emitted by internal combustion engines and their toxicity, depending on the engine technical state, operational mode, fuel grade, and road pavement surface. Together with growing level of motorization urban pollution increases as well, as the cars with internal combustion engines emit harmful gas that causes the "greenhouse effect", smog. Another problem is limited and decreasing oil resources. In this context the focus of researchers and manufacturers on looking for alternatives is natural. The paper deals with one of the alternatives i.e. use of hydrogen that during the combustion process emits zero toxic fumes. In the study the hydrogen generator by help of electrolysis releasing hydrogen of water - fuel supplement, which helps to burn fuel more efficiently was used.
