Co-pyrolysis of blends of a high-sulphur coal with different biomass wastes has been investigated as a way to obtain improved solid fuels. Experiments have been performed in a thermogravimetric laboratory system and in a pilot-scale mobile bed furnace, this last operating at 600 degreesC. The presence of biomass enhances coal desulphurization upon thermal treatment in significant relative amounts, giving rise about as much as twice percent sulphur loss at high biomass-to-coal ratios in the starting blend in comparison with the S loss occurring upon pyrolysis of coal alone. Combustion experiments with chars resulting from co-pyrolysis of these coal-biomass blends confirm this significantly improved desulphurization. Thus, co-pyrolysis of blends of high-sulphur coals with biomass wastes provides a potential way to obtain improved solid fuels combining good heating values with environmentally acceptable S contents. The chars resulting from co-pyrolysis show heating values within the range of high-quality solid fuels whereas the ash contents remain in the vicinity of that of the starting coal except in the case of the coal-straw blend where the relatively high ash content of this biomass waste leads to co-pyrolysis chars with substantially higher ash contents and lower heating values. (C) 2004 Elsevier Ltd. All rights reserved.