This paper presents an investigation of the solids flux distribution in a 0.161 m ID circulating fluidized-bed riser, operating in temperature range 20-550 degrees C. The superficial gas velocity and the imposed solids flux were varied from 2.5 to 5 m s(-1) and from 2 to 60 kg m(-1) s(-1), respectively. For the operating conditions examined, the reduced solids flux, i.e. local solids flux divided by cross-sectional mean solids flux, was insensitive to changes in the imposed solids flux over a wide range at a given superficial gas velocity. As temperature increased the mean suspension density decreased, whilst the reduced solids flux profile became flatter and less parabolic in shape. Local fluctuations in solids flux were found to increase with increasing temperature. Analysis of results suggests that the effect of temperature on CFB hydrodynamics (e.g, the mean suspension density and the solids flux profiles) is mainly due to the change in viscosity of the fluidizing gas.