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Various kinds of wood waste may be also used as biofuel - not only in the industry and furniture obtained waste timber, but also small branches, tree bark, leaves. In Lithuania, oak is a well growing and highquality wood; therefore, it is appropriate to investigate the oak waste preparation and utilization for burning. In the paper, test results of oak bark, leaves and their mixture preparation for the burning process (milling, pelleting) and the prepared pellet properties (moisture content, density, ash content, calorific value) are presented. Research investigations were carried out in laboratory basis of the Institute of Agricultural Engineering and Safety, Aleksandras Stulginskis University, Lithuania. Fractional composition of oak bark, leaves and their mixture mill was determined on sieves with holes of various diameters after chopping and milling of the investigated oak waste. The biggest mill fraction was accumulated on 0.25 mm sieves - from 30.9 to 46.2 %, and too big amount of dust was found - from 22.0 to 24.3 %. Prepared oak bark, leaves and their mixture pellet moisture content ranged from 8.1 to 12.5 %, and bulk density - from 975.8 to 1122.2 kg·m-3 DM (dry matter). The ash content of oak waste was very high, varied from 10.4 to 14.7 % and was about 10 times higher than wood-based biofuels. The determined calorific value when burning of oak bark, leaves and their mixture pellets varied from 17.3 to 17.7 MJ·kg-1. This calorific value of oak waste pellets was relatively high, close to the calorific value of some herbal plants and wood species. The presented research results show that oak bark, leaves and their mixture can be used as a solid biofuel because the main parameters of this plant satisfy the main requirements for solid biofuels. [ABSTRACT FROM AUTHOR]