Production of beta-rhombohedral boron carbide (B4C) on a tungsten substrate by the chemical vapor deposition from a BCl3-H-2-CH4 gas mixture was achieved. An impinging-jet reactor was used to minimize the mass-transfer limitations on the reaction kinetics, which made a detailed kinetic investigation possible. Results of the XRD and XPS analyses showed that the solid product formed on the substrate is a rhombohedral B4C phase. Both dichloroborane and boron carbide formation rates were found to increase with an increase in the inlet molar fraction of BCl3. The formation rate of boron carbide increased with an increase in the inlet molar fraction of CH4. However, no effect on the formation rate of dichloroborane was observed with an increase in the inlet molar fraction of methane. The activation energy of the boron carbide formation reaction was ascertained to be 56.1 +/- 4.0 kJ/mol. The boron carbide formation reaction was proportional with the 0.34 +/-0.055 power of the initial boron trichloride concentration and 0.64 +/-0.084 power of the initial methane concentration. (c) 2006 American Institute of Chemical Engineers.