Amorphous Si3N4, Si/C/N and crystalline SiC nanopowders of 5-50 nm in mean diameter were synthesized via laser-induced gas-phase reactions with yields of 250 g h(-1) using low cost hexamethyldisilazane (HMDS) and NH3 (or H-2). Reaction flame temperatures, which were controlled by the total gas flow rate, greatly influenced powder composition and crystallinity. Amorphous Si3N4 powders (96 wt.%) were obtained at 1000 degreesC, with HMDS + NH3; beta-SiC (93 wt.%) was formed at 1600 degreesC with HMDS + H-2. Amorphous Si/N/C powders with various N/C ratios (0.1-6) were synthesized at various temperatures. The main impurities in the powders were the organo-ligands such as NHX and CHX (X= 1- 3), whose existence also resulted in a strong surface absorption of oxygen. Key techniques for commercial production of the abovementioned powders were also stated. (C) 2003 Published by Elsevier B.V.