Introduction Fears of climate change and increasing concern over the global warming have prompted a search for new, cleaner methods of electrical power generation. Co-firing of biomass fuels (e.g. wood chips, straw, bagasse, peat and municipal solid waste) and coal is presently being considered as an effective means of reducing the global CO2 emissions. Demonstrations have been performed in a number of utility installations across the world, including Australia, Europe and the United States. All types of combustion technologies have been used but a particular attention has been given to pulverised fuel (PF) boilers, as they constitute the bulk of power generation hardware in many countries. Despite the simplicity of the co-firing concept, its application in PF boilers is associated with many technical issues including combustion related problems such as fuel ignition, flame stability, temperature, and geometry as well as char burnout. There is still no fundamental understanding of the underlying mechanisms that cause such technical problems. In particular, Studies on fundamental issues such as pyrolytic behaviour of biomass/coal blends or biomass char reactivity are scarce. Previous investigations on co-pyrolysis of biomass/coal mixtures have mostly concentrated on the mechanism of production of the gas phase species. There has also been a handful of studies on the impact of synergistic effects (i.e. chemical interaction between the two fuels) on the yield of major pyrolysis products, in particular, volatile matter. However, much less attention has been given to the influence of synergistic effects on the composition of the pyrolysis products. In addition, most previous studies focused on examining the impact of various controlling parameters (e.g. heating rate, temperature, blending ratio, etc) in isolation. The objective of this study was to address these shortcomings through a comprehensive investigation of the pyrolytic behaviour of woody biomass/coal blends over a wide range of heating rates and temperatures relevant to PF boilers. The fundamental knowledge gained from this project is essential for the proper understanding of co-firing in practical PF based systems. For example, the knowledge of the low heating rate pyrolysis of biomass/coal mixtures may help to prevent the accidental fires, which sometimes occur in fuel handling units (e.g. mills or pulverisers) of typical PF boilers during co-firing exercises. Similarly, the knowledge of the high heating rate pyrolysis of biomass/coal blends, may help to understand and predict the impact of co-firing on the combustion related phenomena in PF boilers.