A new analytical model for the surface potential and the threshold voltage of a silicon-on-insulator (SOI) MOSFET with electrically induced shallow source/drain (S/D) junctions is presented to investigate the short-channel effects (SCEs). Dividing the SOI MOSFETs silicon thin film into three zones, the surface potential is obtained by solving the two-dimensional Poissons equation. Our model includes the effects of the body doping concentration, the lengths of the side and main gates and their work functions, applied drain and substrate biases, the thickness of the gate and buried oxide, and also the silicon thin film. Our model results reaffirm that the application of induced S/D extensions to the SOI MOSFET will successfully control the SCEs for channel lengths even less than 50 nm. Two-dimensional simulation results are used to verify the validity of this model, and quite good agreements are obtained for various cases.