In this paper, a temperature dependent analytical model of sub-micron GaN MESFETs for microwave frequency applications is presented. The contributions from various temperature dependent material parameters are taken into account in order to develop an accurate 1-V model along with the effect of gate leakage current on the threshold voltage of the device. The model is further extended to predict the temperature dependence of transconductance, output conductance, cut off frequency and maximum frequency of oscillation. The analytical results show excellent agreement with the experimental data at temperatures up to 200 degrees C for a 0.25 mu m device. (C) 2007 Elsevier Ltd. All rights reserved.