In this study, the forward bias current-voltage-temperature (I-V-T) characteristics of (Mo/Au)–AlGaN/GaN high electron mobility transistors (HEMTs) have been investigated over the temperature range of 100-450K. The barrier height (Fb), ideality factor (n), series resistance (Rs) and shunt resistance (Rp) of (Mo/Au)–AlGaN/GaN HEMTs have been calculated from their experimental forward bias current–voltage-temperature (I-V-T). The capacitance–voltage (C–V) of (Au/Mo)- AlGaN/GaN HEMTs were investigated at room temperature. The doping concentration (Nd) and the bi- dimensional sheet carrier density (ns) were evaluated from C–V data. The experimental results show that all forward bias semilogarithmic I-V curves for the different temperatures have a nearly common cross point at a certain bias voltage, even with finite series resistance (Rs). We found that the value of Fb and Rs increases by cons n and Rp decreases with increasing temperature. The values of Nss obtained by taking into account the Rs are about one order lower than those obtained without considering the Rs.