A design of experiments approach was used to investigate the impact of bed temperature, volumetric air flow rate, spray rate and concentration of the coating solution on fluidised bed coating of particles. The process was analysed in terms of agglomeration tendency, efficiency and coating quality. Response surfaces were fitted to the experimental data from which optimal factor combinations were calculated in order to improve the coating quality. The coating quality was assessed by a previously developed method based on a dissolution test to efficiently measure the thickness, the uniformity and the completeness of the coating. It was demonstrated that the method provides a reliable way to assess the various measures for coating quality. (C) 2016 Elsevier B.V. All rights reserved.