In this paper, we present simulations of some of the most relevant transport properties of the inversion layer of ultra-thin film SOI devices with a self-consistent Monte-Carlo transport code for a confined electron gas. We show that size induced quantization not only decreases the low-field mobility (as experimentally found in [Uchida K, Koga J, Ohba R, Numata T, Takagi S. Experimental eidences of quantum-mechanical effects on low-field mobility, gate-channel capacitance and threshold voltage of ultrathin body SOI MOSFETs, IEEE IEDM Tech Dig 2001;633-6; Esseni D, Mastrapasqua M, Celler GK, Fiegna C, Selmi L, Sangiorgi E. Low field electron and hole mobility of SOI transistors fabricated on ultra-thin silicon films for deep sub-micron technology application. IEEE Trans Electron Dev 2001;48(12):2842-501-Esseni D, Mastrapasqua M, Celler GK, Fiegna C, Selmi L, Sangiorgi E, An experimental study of mobility enhancement in ultra-thin SOI transistors operated in double-gate mode, IEEE Trans Electron Dev 2003;50(3):802-8. [1-3]]), but also the electron saturation velocity and the carrier heating depend on the subband structure, and thus on the silicon film thickness. (c) 2005 Elsevier Ltd. All rights reserved.