A mathematical model of the combustion of bagasse in a suspension-fired boiler was developed; its formulation, based on an existing code, includes aerodynamic, particle-drag, drying, devolatilisation, combustion and heat-transfer processes. Turbulence is described by the k-epsilon model. A drying model was developed which assumes evaporation at the wet-bulb temperature. Modifications to the fluid-drag and heat-transfer correlations were called for because of the cylindrical shape of the bagasse fibres. The kinetics of devolatilisation and char combustion were measured by means of thermogravimetry. The completed model was tested on a water-wall boiler capable of raising 200 t h-1 of superheated steam. Measurements of temperature, oxygen concentration and wall heat-flux were taken in the furnace at steady-state conditions. The simulation showed good agreement with the measured variables, and the greatest disagreement appeared towards the rear of the furnace, where combustion was concentrated.