A microwave assisted low temperature decomposition process has been developed for production of high quality fuels from biomass. 180 degrees C was identified as key in the process mechanism, as the amorphous region of cellulose softens allowing a microwave induced rearrangement. Proton transfer is then possible under the microwave field resulting in acid catalysed decomposition. This low temperature process has been shown to be suitable for scale-up, producing a high quality char for use as a coal replacement and bio-oil suitable for upgrading to liquid fuel. (C) 2009 Elsevier Ltd. All rights reserved.