Ge nanowires have been prepared at a low temperature by a simple hydrothermal deposition process using Ge and GeO(2) powders as the starting materials. These as-prepared Ge nanowires are single crystalline with the diameter ranging from 150 nm to 600 nm and length of several dozens of micrometers. The photoluminescence spectrum under excitation at 330 nm shows a strong blue light emission at 441 rim. The results of the pressure and GeO(2) content dependences on the formation and growth of Ge nanowires show that the hydrothermal pressure and GeO(2) content play an essential role on the formation and growth of Ge nanowires under hydrothermal deposition conditions. The growth of Ge nanowires is proposed as a solid state growth mechanism. (C) 2009 Elsevier Ltd. All rights reserved.