Previous studies have shown that a spouted bed can achieve clean and efficient combustion in the flame mode, i.e., using a flame positioned on the bed surface. For comparison. a spouted bed also should be operated in the non-flame mode. To obtain improved design information and explore further applicability of such a combustor, the thermal behavior in different regions of the system have been investigated with emphasis on the bed region; it can influence the combustion performance beyond the bed surface. A non-flame mode study has been conducted by adding heaters. Results for lean propane (phi < 0.31) combustion were obtained in the bed region, at the bed surface and at the exit of the combustor. Several operating parameters - equivalence ratio, particle size, bed height, and bed material were investigated. A critical temperature region was defined as the temperature range where conversion to intermediates and products increased distinctly. From a comparison of combustion results between the flame mode and the non-flame mode, the role of the flame may be discerned. The critical temperature region observed in the non-flame mode corresponded to the highest bed temperature achievable in the flame mode. There was no significant difference in combustion results between the two modes in the bulk bed region.