Bismuth nanowire arrays have been synthesized within the pores of ordered mesoporous silica templates using a supercritical fluid (SCF) inclusion technique. The formation of nanowires within the mesopores was confirmed by powder X-ray diffraction (PXRD), N-2 adsorption experiments and transmission electron microscopy (TEM). The formation of the bismuth nanowire arrays occurred through the initial binding of the bismuth precursor to the inner walls of the mesoporous channels, forming bismuth crystal seeds, which subsequently developed into wire-like structures. By varying the concentration of the bismuth precursor in the SCF phase, the loading of bismuth nanocrystals within the mesoporous channels can be controlled. The effect that temperature had on the formation of bismuth nanocrystals within the mesopores was also investigated. The highest loading of bismuth nanocrystals inside the mesopores was obtained at reaction temperatures near the critical point of toluene. (c) 2007 Elsevier B.V. All rights reserved.