A generic numerical model which is valid both in the strong inversion regime and sub-threshold regime for the detection of terahertz radiation utilizing Metal-Oxide-Semiconductor (MOS) Field-Effect Transistors (FETs) is developed in this paper. A general carrier density equation and gate leakage current are coupled to the basic hydrodynamic equations which govern the electron transport in the 2D channel of the MOS field-effect transistor to obtain the numerical solution; a progress-based photo-response signal of the terahertz radiation of MOSFET is calculated. The simulation results are compared with existing analytical results, proving the validity of the proposed numerical model and overcoming limitations of the analytical theories. (C) 2010 Elsevier Ltd. All rights reserved.