In this paper, we report a detailed experimental forward gate stress in GaN-based power High Electron Mobility Transistors (HEMTs) with a p-type gate, controlled by a Schottky metal/p-GaN junction. The devices characterization widely covers different temperatures range studying the gate and drain leakage currents behavior. Moreover, two-dimensional (2D) Technology Computer Aided design (T-CAD) simulations are performed to investigate the main physical phenomena involved in p-GaN HEMT. From simulations results it is possible to notice that when a high stress voltage is applied on the gate, a high electric field occurs in the depletion region of the p-GaN close to the metal interface.