Twin-fluid atomisation spray-pyrolysis has been investigated for the production of ZrO2 powders. The atomiser used in this study has a novel internal arrangement that can produce a spray with a mean diameter (SMD) of less than 5 mum. Spray pyrolysis tests with zirconium nitrate as a precursor salt were performed and the formation of ZrO2 powder was studied under substantially different heating rates and initial solution concentrations. A mean particle diameter, d(0.5), of 0.67 mum and 0.77 mum was achieved for 0.05 M and 0.5 M solutions, respectively. It was concluded that the new nozzle design performed well and was successful in producing ultra-fine ZrO2 powder with a principally tetragonal structure when the correct process conditions of heating rate and residence time were applied.