The large water content of brown coal can be recduced by hydrothermal-mechanical expression (HME). The HME process advantages of hydrothermal dewatering and mechanical dewatering and consequently, with low input of energy produces dry, dense and hydrophobic coal. The mechanism of the HME process is analyzed using the theory of one-dimensional consolidation. A Terzaghi-Voigt combined model is used to model the HME process operated at high temperature and pressure. The temperature-related behaviours of some important model coefficients and the creep constant are identified. The model prediction for moisture reduction during expression agrees well with experimental data.