Use of high temperature gasifying air is considered as one of the economical ways to improve the gasifier performance in terms of gas quality and process efficiencies. One of the on-going gasification research activities at Oklahoma State University is to study the effect of input air temperature on downdraft gasification of a variety of low bulk density biomass materials like switchgrass and sorghum. A unique exploratory downdraft gasifier system has been developed at Oklahoma State University.  It has an internal separate combustion section where turbulent, swirling high-temperature combustion flows are generated.   Effects of air temperature on composition and lower heating value of the dry producer gas, and gasifier efficiency for forage sorghum are presented in this poster.