Nozzles are important parts in rapidly developing technology nowadays. In particular, there appears to be strong a potential for enhancing powder production capability through improved nozzle design. The nozzle design is very important for the efficient powder production in gas atomisation. There are significant differences in nozzle design for the powder production due to the fluid type, inlet and outlet conditions. In this study we designed a new supersonic nozzle with a Mach number of 2.5 and we measured mass flow rate of the gas flowing through the nozzle. The theoretical and experimental results were compared and discussed. The result of the experimental mass flow rate measurements was very close to the theoretically calculated values.