Toluene was used as the fuel in a heterogeneous spouted bed combustor to investigate the effect of bed material on pollutant emissions. Experimental measurements were conducted in the annulus region (preflame) and include Destruction and Removal Efficiency (DRE) of the fuel, and concentrations of three products of Incomplete combustion (PICs) of toluene; CO, benzene and benzaldehyde. Two types of bed material were used: Sand and quartz. Higher conversion of the fuel (higher DRE) and higher concentration of CO, benzene and benzaldehyde (up to one order of magnitude) were observed with sand particles. Predictions of a detailed homogeneous gas phase mechanism for the oxidation of toluene (Emdee et al., 1992), were compared to the experimental data to reveal possible influences of surface reactions on the conversion of toluene and formation of CO, benzene and benzaldehyde.