A prediction method relating dynamic viscosity with reduced temperature is proposed in this paper for pure and mixed refrigerant fluids in the liquid state along the saturation line. The validity of the method is checked by comparison with dynamic viscosity data available in literature. Comparison results are reported for many halocarbon refrigerants and for bis(difluoromethyl)ether (RE134) as well. Some experimental data for azeotropic and non-azeotropic binary mixtures have also been compared with the dynamic viscosity predicted with the present method and a simple mixing rule. The results of the comparisons give average absolute deviations and maximum absolute deviations compatible with engineering applications.