This article reports the study of Pd Schottky contact on porous n-GaN for hydrogen gas sensing. Upon exposure to 2% H-2 in N-2, porous GaN sensor exhibited significant change of current. Morphological studies revealed that Pd contact deposited on porous GaN has ridge-trench-like morphology, a dense porous network was found in between the ridges. The dramatic change of cur-rent was attributed to the unique microstructure at Pd/porous GaN interface, which allowed higher accumulation of hydrogen; this resulted in a stronger effect of H-induced dipole layer and led to a significant change in the electrical characteristics of the porous sensor. (C) 2007 Elsevier B.V. All rights reserved.