┴ numerical code to calculate the burn-out time of a single biomass particle in a flu▀dized bed reactor was developed. Combust▀on model▀ng was performed by numerical calculation of energy and mass balances on the part▀cle. ╩inet▀c data for Pyrolysis and char combustion stages, as determined by therm´grav▀metŮc analysis, were used. The results showed that the t▀me needed for the completion of each part▀al combust▀on stage is less for biomass than for brown coal. The same remarks hold for all biomass species studied, whereas the predict▀ons of the simulat▀on model were ▀š agreement W║th the results of the efforts of other researchers. The effect of uncertain▀n parameters ´š model predictions was investigated and it was proved that the particle diameter, moisture content, oxygen concentration, and especially the gas temperature have the greater influence ´š the calculated results. The combined use of the experimental data and the theoretical calculations provide a complete V║ew of biomass/waste combust▀on behavior, which ║S absolutely necessary for the design and operat▀on of large-scale units.