The thermal behavior of biomass has been investigated by using TGA analysis with slow pyrolysis and combustion. The elemental analysis of the emission for carbon, nitrogen and sulphur of different species of selected biomass in Malaysia and their ashes are conducted in the experiments. Emission ratios are used for relative comparison of different emissions and are defined as the above mixing ratio of the compound studied, divided by the above background mixing ratio of reference compound. Simulation models are able to describe the mass balance and energy balance of selected tropical biomass from lowland forest of Malaysia. Based on the experiments the biomass burning contributes significantly to the global budgets of C-N-S. The VOC productions of biomass burning are component of low molecular weight. The main output from this book is the development of a set of emission factors for biomass burning of wood from the tropical forest found in Malaysia. This data is useful for estimation of emission inventory of forest fires which can be further used for developing policies related to intervention, curtailing impacts and effects of forest fires in general.