The European Commission, through its Directive 2009/28/EC, decided to extensively support the consumption and production of »green« energy from renewable energy sources, primarily because of diminishing supplies and constant rise in fossil fuels prices and critical necessity to mitigate their negative influence on the environment. The alleviation of a part of these problems can be achieved by growing and use for energy purposes of biomass from Miscanthus x giganteus grass. Given the fact that these cultures can be harvested in the whole period from the month of November until the beginning of new vegetative cycle, the objective of this paper is to determine the ultimate properties (C, H, O, S, volatile matter) and proximate properties (moisture, fixed carbon, coke, ash, N), content of minor (Cd, Cr, Co, Cu, Fe, Pb, Mn, Ni, Zn) and major elements (Ca, K, Na, Mg) as well as high heating value of biomass M. x giganteus from the first year of cultivation from three different locations in the Republic of Croatia (Donja Bistra, Medvednica and Donji Lapac), harvested in three different times (November 2011, February and March 2012). The conducted investigations confirmed the potential of M. x giganteus crop grown in the fields in Croatia as a high-quality and environmental friendly feedstock for direct production of electricity and heat