In recent years there has been a significant increase in world population, thus there is a growing demand for transport. To meet this demand it is necessary to the sustainable development of the transport so as to not increase the pollution of the environment. Requirements for limitation of emissions of toxic compounds force to make design changes in engines, the use of modern and effective exhaust gas aftertreatment systems of the engine and improve the way of the operation of vehicles. The reduction of pollutant emissions and fuel consumption can also be achieved through the use of alternative fuels, including gas fuels, as well as their co-firing with conventional fuels. The article presents primarily the results of the exhaust emissions tests of railway vehicle, fuelled by B100. It has been shown differences in the concentrations of toxic compounds in the exhaust systems.