The viscosities of liquid-solid suspensions were experimentally determined for castor oil-paraffin and acrylonitrile butadiene styrene (ABS) plastic particle systems at room temperature and for a Fe-C melt at various temperatures. The degree of sphericity of the particles was introduced as a parameter for characterizing the effect of the particle shape on the apparent viscosity of liquid-solid systems. The results indicated that with an increase in the degree of sphericity of the particles, the apparent viscosity decreased. However, the presented well-known prediction models, such as Krieger-Dougherty's model and Batchelor's model only consider the effect of the particle fraction on the apparent viscosity of liquid-solid suspensions, whereas the effect of the particle shape is neglected. Based on the experimental data, the particle shape was introduced to modify Krieger-Dougherty's and Batchelor's models. The apparent viscosity can be successfully predicted using the modified model. (C) 2018 Elsevier B.V. All rights reserved.