h-BN layers were deposited on alpha-SiC and sapphire substrates by chemical vapor deposition at high temperature (1500-1900 degrees C) using B2H6 and NH3 diluted in Ar. Growth rates were in the 6-10 mu m/h range. In all the conditions studied, the as deposited BN layers were found to be translucent to light, some having a light whitish aspect and other a more yellowish one. It was also observed that the deposit was not always adhesive. Characterizations showed that the layers were nano-crystalline with crystallite size <10 nm. The growth rate was found to be temperature and N/B ratio dependent due to an N limited growth regime which is more pronounced above 1700 degrees C. (C) 2011 Elsevier B.V. All rights reserved.