High temperature air jets are used widely in the fields of drying, sintering, powder treatment, sterilization and others, but the velocity and temperature fields and their relation have not been sufficiently clarified. The main purpose of this study is to improve the performance of surface fusing, or globular forming, systems of thermoplastic fine particles. First, the flow and thermal characteristics and their relation of high temperature air jet from a pipe nozzle were clarified by measuring the mean and fluctuating velocity and temperature profiles. In order to control the jet diffusion in the radial direction, a ring nozzle with a ring-shaped contraction near the nozzle exit was used and its flow and thermal characteristics were determined. Next, the effect of nozzle shape on the performance of the globular forming was examined, and the ring nozzle was shown to be suitable.