In article possibilities of predicting the viscosity of stable multicomponent water-oil systems in practice, when it is impossible, for a number of reasons, to obtain their experimental values, are considered. A predictive model is proposed to describe the change in the viscosity properties of various oil-water emulsions depending on the degree of water saturation. It is shown that the proposed formula allows to determine the effective viscosity of water-oil systems in the entire range of variation of the velocity gradient in the absence of experimental data and is acceptable for engineering practice. Keywords: viscosity; water-oil emulsions; matematical description; water saturation degree; heterogeneous systems.