Viscosities of four binary mixtures: pyridine + PEG200, pyridine + PEG400, nicotine + PEG200 and nicotine + PEG400 have been measured in temperature range 288.15-333.15 K with temperature step of 5 K and at the atmospheric pressure. Viscosity deviations and excess molar Gibbs energies of activation of viscous flow for the selected binary systems were calculated from the experimental data and fitted to the Redlich-Kister polynomial equation. In addition, UNIFAC-VISCO and ASOG-VISCO models were used to predict the dynamic viscosities of the investigated binary mixtures. The experimental values of viscosity for the investigated four binary systems were used to determine the new interaction parameters for their application in UNIFAC-VISCO and ASOG-VISCO models. The viscosity data have also been correlated by two parameters Teja-Rice and three and four parameters McAllister models. (c) 2012 Elsevier B.V. All rights reserved.