Multiple-networked GaN nanowires with excellent sensing properties to hydrogen were realized by functionalizing their surfaces with Ga(2)Pd(5)-related nanodots. Compared to the bare-GaN nanowire sensors, functionalization improved the relative resistance responses by a factor of >50 at H(2) concentrations ranging from 100 to 2000 ppm. At room temperature, the nanodot-functionalized GaN nanowire sensors exhibited a relative resistance response of 34.1% at 100 ppm H(2). Interestingly, a shell layer was transformed mostly into Ga(2)Pd(5)-phased nanodots, which was confirmed by X-ray diffraction and transmission electron microscopy. The mechanisms responsible for the improvement induced by nanodot functionalization are proposed in terms of the hydrogen spillover effect. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.