The aim of the project was analytical evaluation of carbon content and soil carbon sequestration in Miscanthus and coppice willow crops biomass. In this paper, we present the results from a field experiment carried out in 2004-2006 at two Experimental Stations of the Institute of Soil Science and Plant Cultivation, Puławy, and net C sequestration under this cultivation. The C-sequestration model adapted by Matthews and Grogan (2001) was used for the simulations. The abovementioned crops are cultivated for the production of solid fuels. The three-year average yield for Miscanthus was between 15 and 17 t ha-1 y-1, dependent on location, whereas for willow it was 12 and 13 t ha-1y-1. The net soil carbon sequestration for Miscanthus cultivation was 0.64 t C ha-1 y-1 while for coppice willow it was 0.30 t C ha-1 y-1.