Combustion behavior of woodblocks and rubber balls was investigated in a vortex fluidized bed combustor (VFBC) with an intermittent fuel feeding system. Effects of various operating parameters on the temperatures within the combustor were studied. Response surface method (RSM) and single factor experimental method were used for statistical analysis. The results show that the combustor temperatures change periodically with the feeding cycles and the highest temperature appears in the splashing region. The mean bed and freeboard temperatures increase with in-bed stoichiometric oxygen ratio (ISOR) for both feedstocks. When the static bed height increases, the mean bed temperature decreases, and the mean freeboard temperature increases for both fuels. When the feeding interval increases, the mean bed and freeboard temperatures decrease for rubber ball burning; on the other hand, both increase in the case of wood burning. According to the experimental results and RSM analysis, the mean bed temperature can be represented by a combinatorial equation of operation parameters, while the mean freeboard temperature can be represented by an equation of static bed height as the only operation parameter.