High-purity gallium phosphide (Gap) nanowires were successfully synthesized on the nickel monoxide (NiO) or the cobalt monoxide (CoO) catalyzed alumina substrate by a simple vapor deposition method. To synthesize the high-purity Gap nanowires, the mixture source of gallium (Ga) and Gap powder was directly vaporized in the range of 850-1000 degreesC for 60 min under argon ambient. The diameter of Gap nanowires was about 38-105 nm and the length was up to several hundreds of micrometers. The Gap nanowires have a single-crystalline zinc blend structure and reveal the core-shell structure, which consists of the Gap core and the GaPO4/Ga2O3 outer layers. We demonstrate that the mixture of Ga/GaP is an ideal source for the high-yield Gap nanowires. (C) 2002 Elsevier Science B.V. All rights reserved.