In connection with the observed dynamism of changes on the energy market regarding generation of energy from sources other than coal, more attention was paid to the use of "clean", low-emission technologies. Bearing in mind the need to search new, alternative energy sources, the aim of the study was to investigate and analyze the properties of grain biomass, such as rice and corn, as a fuel. To achieve the goal, the research problem has been formulated: how the fragmentation degree and the type of biomass affects such energy properties as heating value and heat of combustion. To resolve the problem, the properties of white rice, black rice, red rice and corn before and after grinding were analysed. The results show that white rice has the biggest value of heat of combustion before grinding, red rice – the lowest. White rice has the biggest heating value for whole grain, red rice – the lowest. The research allows to state that grinding operations result in increasing energetic properties of biomass. It can be also assumed that biomass is a good substitute of fossil fuel.