Densities and kinematic viscosities of molten mixtures of nickel(II) chloride in tetra-n-butylammonium iodide have been measured as functions of temperature and composition. The data on the kinematic viscosity have been analyzed using both Arrhenius and non-Arrhenius type equations. The heat of activation, the entropy of activation, and the free energy of activation for viscous flow have been computed. At higher concentrations a slight tendency towards non-Arrhenius viscous behaviour is observed. The free energy of activation helps in describing the overall composition dependence of kinematic viscosity.