Drying as an immiscible displacement process has a great importance in chemical industries. The efficiency of the process is highly affected by the pore space structure of the solids. In this study non-isothermal drying behaviour of capillary porous media is studied in two dimensional (2D) mono-modal and bi-modal pore network models. Non-isothermal drying in the absence of viscous force has been studied previously. The presented model includes viscous flow in liquid phase while capillary pumping in liquid phase and diffusion in gas phase are the other mass transfer mechanisms at the pore scale. Conduction is considered as the heat transfer mechanism. The effect of viscous flow and temperature of drying air are studied. The simulation results are compared with a non-viscous model. The results indicate that the effect of viscous force is more significant in low temperatures. During the first falling drying rate period viscous forces dominate capillary pumping and decrease drying rate. The first drying rate period is not affected by viscous forces; however, the morphology of the pore space is an important parameter in forming this period. In bi-modal pore network, drying rate is higher due to the suitable arrangement of macro and microthroats in its structure. (C) 2014 Elsevier Ltd. All rights reserved.