A software tool for the 2D simulation of the SOI double-gate MOSFET is developed. The developed tool is operating under the MATLAB environment and is based on the numerical solution of the Poisson and Schrodinger equations in a self-sufficient way to obtain the potential, carrier concentrations and current within the device. In comparison with existing tools, the new tool uses finite element methods for solving the Poisson equation, so that the simulation of curved contour structures becomes feasible. Another new feature of the tool is the use of the transfer matrix method (TMM) in the solution of the Schrodinger equation, which was demonstrated in a recently published document that gives more accurate results than the conventional finite difference method (FDM) when used in some operating regions. According to the working conditions, the tool can switch between FDM and TMM to satisfy the highest precision with the highest simulation speed. The tool is called FETMOSS (finite elements and transfer matrix MOS simulator).