In the heterogeneous catalyst mass transfer phenomena with their strong influence on the reaction efficiency are very important. CFD (computational fluid dynamics) is used to determine the liquid-solid mass transfer coefficients. The determined coefficients can be used in the design of reactors and unit operations where boundary effects are negligible, that is at high apparatus-to-particle-diameter-ratios. The agreement between the theoretical results and the experimental data of other authors is qualitatively good, whereas quantitative differences result from the model simplifications.