A mini pilot coal gasification plant (4–10 kg/h coal feed), incorporating a novel Compartmented Fluidised Bed Gasifier (CFBG) for gasification and combustion has been used for hot experiments. An important operating requirement for steady operation is maintaining the correct solids circulation rate (SCR) between the two compartments. A new technique has been developed for measuring the SCR and can be applied equally easily to hot and cold operation. The method has been applied in a 24factorial experiment with 2 replicates to obtain a statistical model for SCR as a function of the operating variables over the whole practical operating range. The model derived from the factorial experiment has been further tested against a vareity of operating conditions, including hot experiments at typical operating conditions.