An approach to improve the accuracy of submicron particle size distribution measurement using a cuvette photocentrifuge (Horiba CAPA-700) has been applied to a commercial alumina powder and a standard quartz powder. This approach incorporates a correction for the light scattering from small particles, an improved raw data smoothing routine and a correction for the radial dilution effect. The results for the commercial alumina powder show very good correspondence with the supplier’s X-ray sedimentometer data when corrected for light scattering and radial dilution; and allow a more complete data collection in the 0.3-0.03 mum range. For the standard quartz powder (BCR 66) a less satisfactory result is found, with the light-scattering corrected data giving a much finer particle size distribution than expected for the standard powder. Two possible reasons for this discrepancy, the nonsphericity of the quartz powder and an imaginary part of the refractive index of quartz due to impurities, are discussed along with the limitations of the approach for accurate submicron particle size measurement of polydispersed irregularly shaped particles.