The pore size distribution and the fiber diameter on the coupled heat and liquid moisture transfer in porous textiles are investigated to reveal the mechanisms of the coupling effects. This paper focuses on a theoretical investigation of the coupling mechanism of heat transfer and liquid moisture diffusion in porous textiles by using an improved mathematical model. In this model, the pore size distribution is assumed to be a cubic-polynomial distribution, which is close to the experimental measurements [Text. Res. J. 56 (1) (1986) 35]. The liquid diffusion behavior in porous textiles can be described as a diffusion equation. The improved diffusion coefficient can be expressed as: D-1(epsilon(1)) = 5/21 d(c)/epsilon sin(2) beta/eta 7epsilon-6epsilon1/5epsilon-4epsilon1 epsilon1sigma cos phi. For comparison, two types of pore distribution and the fiber diameter in the porous textiles are discussed. With specification of initial and boundary conditions, the distributions of the temperature, moisture concentration, and liquid water content in the porous textiles can be numerically computed. The comparison with the experimental measurements shows the superiority of this new model in resolving the coupled heat and liquid moisture transfer in porous textiles. The results illustrate that the heat transfer process is influenced by the pore size distribution and fiber diameter of the porous textiles. (C) 2003 Elsevier Ltd. All rights reserved.