This review considers the pollutants formed by the combustion of solid biomass fuels. The availability and potential use of solid biofuels is first discussed. This is followed by the methods used for characterisation of biomass and their classification. The various steps in the combustion mechanisms are given together with a compilation of the kinetic data. The chemical mechanisms for the formation of the pollutants: NOx, smoke and unburned hydrocarbons, SOx, Cl compounds, and particulate metal aerosols are outlined. Examples are given of emission levels of NOx and particulates from combustion in fixed bed combustion, fluidised bed combustion and pulverised biomass combustion and co-firing. Modelling methods for pollutants are outlined. The consequential issues arising from the wide scale use of biomass and future trends are then discussed. (C) 2011 Elsevier Ltd. All rights reserved.