This paper describes and analyzes the results of investigations of application of heavy alcohols as an ingredient of diesel fuel. Three different mi xtures of butanol (as heavy alcohol), rape oil (as vegetable oil) and conventional diesel fuel (this mixture was called the biomixdiesel-BMD) were tested using a Perkins engine on a test bed. Contrary to existing experiences both the maximum power output and the maximum torque of the engine were higher in the whole range of the speed of the engine crankshaft when the engine biomixdiesel (BMD) was reinforced. The addition of the component biomix to fuel influenced the specific fuel consumption. Generally, with the larger part of the biomix components the specific fuel consumption were higher. Also the engine power was higher and one should expect that in exploitation the specific fuel consumption should not increase. It is very important that this fuel could be used to reinforce old, already existing and the future diesel engines.The production of butanol is known (directly from biomass and in another way from electrolysis of ethanol). The possibility to get butanol from ethanol gives a very good perspective for the use of ethanol from today's overproduction and moreover without the essential change of infrastructure. There has also been presented another way to use alcohols (and vegetable oils - without transesterification) as diesel engine fuel. All this leads to the conclusion that the use of ethanol overproduction and Europ ean production of vegetable oils will contribute to fulfilling of the expected requirements of European Union regarding the biofuels. Future work should refers to, first of all, the better adjusting of the engine to fuel (especially engine control parameters) and also BMD fuel to the engine for specific exploitation needs.