One-dimensional GaN nanostructures are promising materials for nano-device applications. In the present work, we demonstrated the successful growth of GaN NWs on platinum coated Si(1 1 1) substrates. The GaN NWs density and degree of alignment were found to be highly sensitive to the growth temperatures. The GaN NWs were characterized by field-emission scanning electron microscopy (FE-SEM), photoluminescence (PL), cathodoluminescence (CL) and high-resolution transmission electron microscopy (HR-TEM). The density of GaN NWs was increased monotonically with increase in growth temperature. Relatively, high density of GaN NWs was observed for the growth temperature of 950 degrees C. It was interestingly observed that the peculiar bicrystalline structure of GaN NWs both contain identical crystal structure with a finite interface. We concluded that the Pt acts as a catalyst for GaN NWs growth, and that it provides control over density and position of GaN NWs growth, which can be ultimately utilized for nano-device fabrication. (C) 2010 Elsevier B.V. All rights reserved.