Front-gate and back-gate potential distributions and threshold voltage of recessed source/drain (ReS/D) ultrathin body (UTB) silicon-on-insulator (SOI) MOSFETs are modeled. The analytical expressions of the front-gate and the back-gate potential distributions are derived by assuming a parabolic potential variation perpendicular to channel and by solving 2D Poisson's equation. Based on strong inversion criterion applied to the surface potential minimum value, threshold voltage model of the short channel ReS/D UTB SOI MOSFETs is derived. The model is verified by comparison with 2D numerical device simulator over a wide range of different material and geometrical parameters and very good agreement is obtained. (C) 2009 Elsevier Ltd. All rights reserved.