On the basis of Eyring's absolute reaction rate theory, a new mixture viscosity model has been developed. The nonidealities of the mixture are accounted for with the thermodynamically consistent COSMOSPACE approach. The required model and component parameters are derived from sigma profiles, which form the basis of the a priori predictive method COSMO-RS. To improve the model performance, two segment parameters are determined from a least-squares analysis of experimental viscosity data, where a constraint optimization procedure is applied. In this way, the parameters retain their physical meaning. Finally, the viscosity calculations of this approach are compared to the findings of the Eyring-UNIQUAC model for a broad range of chemical mixtures. These results show that the new Eyring-COSMOSPACE approach is superior to the frequently employed Eyring-UNIQUAC method.