Abstract This experimental study deals with the influence of oxy-compound content (ethanol, MTBE, ETBE) on the Reid vapour pressure (RVP) and on the distillation characteristic (ASTM D86) of petrol blends. Effect of hydrocarbon composition of petrol blends on their volatility and distillation properties was also investigated. Production, storage, distribution and utilisation of automotive fuels are associated with many technical problems especially in cases when the fuels contain some biocomponents. Biofuels blended into petrol and/or diesel fuels can affect their quality and as a consequence that can result in inferior acceptance of these fuels by consumers. In case of petrol blends with bioethanol there are some serious problems that could be resolved, such as stability of the blends, their susceptibility to aerial humidity as well as their high volatility.