A physics-based analytical heat flow model for SOI devices is presented using the SOI silicon film thermal resistance, instead of the traditional SOI channel thermal resistance, to describe heat loss to substrate through buried/filed oxide (BOX/FOX). A relation between the silicon film thermal resistance and the channel thermal resistance is derived. The model reasonably predicts the temperature variation in the silicon film accounting for heat loss through BOX/FOX to the substrate and heat flow to the interconnects shorter than the interconnect characteristic thermal length. The developed model is applied to study heat exchange between devices. (C) 2003 Elsevier Ltd. All rights reserved.