This paper verifies the simulated transfer characteristics and ID–VD characteristics with the experimental data of an AlGaN/GaN high electron mobility transistor of gate length 0.7 µm. Various parameters are analyzed based on the effect of temperature. 2D device simulation is performed using the TCAD Atlas numerical simulation tool. Simulation of various important DC parameters such as the transfer characteristics, ID–VD characteristics, transconductance and threshold voltage is carried out at different temperatures. We have also performed radio frequency analysis to analyze figure of merits such as the current gain cut-off frequency at various temperatures. The simulation analysis is performed in the temperature range of 300–500 K. From the simulation results, we found that the saturation current and I–V characteristics in the linear region decreased because of mobility degradation. However, both the threshold voltage and two-dimensional electron gas sheet density increased with temperature. Hence, the selection of operating temperature is critical as it influences the device performance.