In this study, a recently developed pore network drying model [Metzger, T, Irawan, A. and Tsotsas, E., 2007, Isothermal drying of pore networks: influence of friction for different pore structures, Dry Technol, 25: 49-57], which accounts for liquid viscosity, is applied to three dimensions for the first time. Isothermal convective drying is simulated for a cubic network (25 x 25 x 50) with pore throats with a narrow radius distribution. The role of liquid viscosity is assessed by comparison with non-viscous drying of the same network. Simulation results are presented as phase distributions, saturation profiles and drying rate curves. In the viscous case, a stabilization of the drying front is observed. However, as the network dries out from the surface, the finite drying front gradually widens up and does not approach an asymptotic limit. (C) 2008 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.