Thin tungsten nitride (WNx) films were produced by reactive DC magnetron sputtering of tungsten in an Ar-N2 gas mixture. The films were used as Schottky contacts on AlGaN/GaN heterostructures. The Schottky behaviours of WNx contact was investigated under various annealing conditions by current-voltage (I-V ) measurements. The results show that the gate leakage current was reduced to 10-6 A/cm2 when the N2 flow is 400 mL/min. The results also show that the WNx contact improved the thermal stability of Schottky contacts. Finally, the current transport mechanism in WNx/AlGaN/GaN Schottky diodes has been investigated by means of I-V characterisation technique at various temperatures between 300 K and 523 K. A TE model with a Gaussian distribution of Schottky barrier heights (SBHs) is thought to be responsible for the electrical behaviour at temperatures lower than 523 K. The films were used as Schottky contacts on AlGaN / GaN heterostructures. The Schottky behaviors of WNx contact were investigated under various annealing conditions by The results show that the gate leakage current was reduced to 10-6 A / cm2 when the N2 flow was 400 mL / min. The results also show that the WNx contact improved the thermal stability of Schottky contacts . The current transport mechanism in WNx / AlGaN / GaN Schottky diodes has been investigated by means of IV characterization technique at various temperatures between 300 K and 523 K. A TE model with a Gaussian distribution of Schottky barrier heights (SBHs) is thought to be responsible for the electrical behavior at temperatures lower than 523 K.