The increasing fuel demand, decreasing natural reserves and environmental consciousness have together led to the testing and implementation of new fuels and blending components for internal combustion engines. Biofuels are very commonly added to fossil fuels, most commonly ethanol to gasoline and FAME to diesel. Harmonizing their properties with the engines is a great challenge for the automotive and oil industry. The increasing demand for diesel and decreasing demand for gasoline in Europe raised the question of how it is possible to increase the amount of bio extenders in diesel. Butanol as a potential second generation biofuel could be a future option for blending with diesel. A comprehensive analytical and empirical testing sequence was carried out in the MOL Group's Product Development laboratories to check the application properties of butanol-diesel mixtures. More than 20 chemical and physical parameters of blends were tested regarding flash point, cetane number, viscosity and cold filter plugging point (CFPP). The effects of butanol blending were also tested on power, fuel consumption and injector cleanness. Based on our results it can be said that low butanol blends (up to 5vol% butanol content) appear to be a good alternative for compression ignition engine utilization: they hold the cetane number limits without extra cetane booster additivisation; they allow nearly the same fuel consumption level along with a considerable increase in injector cleanness. The test results support that the utilization of butanol as a diesel extender could be very advantageous, if the difficulties of flash point reduction can be handled in the logistical chain.