Channel electron and hole mobilities in MOSFETs have been extracted in terms of the effective vertical field for several substrate biases. After ascertaining that the 2-D drift-diffusion numerical device simulator is reproducing the substrate char-c variation in the MOSFET with respect to the gate voltage, obtained from C-V data, the mobility versus effective field behavior is extracted by comparing the simulated and measured I-d-V-gs characteristics. A simple model has been constructed to fit the extracted mobility data in weak and strong inversion, for inversion-layer electrons and holes in n-MOSFET and p-MOSFET, respectively, (C) 2002 Elsevier Science Ltd. All rights reserved.