A theory-based model is presented for correlating the viscosity of polymer solutions. The model is based on Eyring's absolute rate theory and the segment-based NRF model for calculating the excess Gibbs energy of activation of the viscous flow. The utility of the model is demonstrated with a successful representation of the viscosity of several polymer solutions. The results show that, the model is valid for the whole range of polymer concentration and it is reliable for correlation of the viscosity of polymer solutions at different polymer molar masses and temperatures. The results are compared with those obtained from the segment-based Eyring-NRTL and segment-based Eyring-Wilson models. (c) 2005 Elsevier B.V All rights reserved.