Viscosities of ternary mixtures of VOSO4 + H2SO4 with water were measured across the entire range of total ionic strength (I-T = 1 to 11) mol.kg (1) and over a temperature range of (283.15-318.15) K. The viscosity B-coefficients of the binary aqueous were determined from Jones-Dole equation. Using the B-coefficients, the activation parameters for viscous flow of the solutes were further evaluated. On the basis of Eyring's equation, a semi-empirical method to estimate the viscosity for concentrated and mixed electrolyte solutions was put forward. The estimated viscosity values of VOSO4 + H2SO4 + H2O are in quite good agreement with the corresponding experimental results with the average absolute relative deviation of 0.96%. (C) 2019 Published by Elsevier Ltd.