Abstract This paper identifies advantages of using biofuels and biomass mixed with coal in combustion. The availability of biomass with regard to landuse is reviewed, followed by a brief account of the combustion process and the concomitant formation of semi-volatile organic compounds. Chemical compositions of selected biofuels and coal are presented. Routes of formation for polychlorinated dibenzodioxins/furans (dioxins and furans) are illustrated with subsequent reference to associated emissions. Graphs in the paper show coal and biofuel propensities for forming dioxin and furan isomers followed by methods for predicting emission levels and isomer distributions within combustion systems. The final sections of the paper summarise recent equilibrium concentration studies and discuss the ongoing combustion experiments being conducted in the University of Leeds’ Department of Fuel and Energy. Preliminary results are presented and discussed, finishing with three main experimentally-drawn conclusions.