A mathemalical model is presented that describes heat and moisture transfer during the holpressing of MDF. The model includes conduction of heat between the press platens and the central layer of the mattress, phase change of water from the adsorbed to the vapor state and the convective heat and mass transfer through the edges of the mattress. This approach results in a three-dimensional unsleady-state problem in which the properties of the wood fibers, water and the wood-water system are dependent on temperature, mattress moisture content and steam pressure. For solving this problem, a finite difference scheme is used for the discretization of. spatial variables and the resulting set of ordinary differential equations is solved using an appropriated ODE solver.