The effect of the gas-phase reaction on the deposition rate and the properties of TiN films from metallorganic chemical vapor deposition with tetrakis(dimethylamido)titanium was investigated. In situ Fourier transform infrared spectrometry was used to study the gas-phase reaction mechanism, and the deposition of TiN films was carried out in a low pressure, cold-wall chemical vapor deposition reactor at a deposition temperature from 200 to 400 degrees C. It was observed that tetrakis(dimethylamido)titanium in the gas phase was dissociated into dimethylamine above 280 degrees C, and, in this case, the deposition rate was decreased and a Ti-rich film was formed. It was shown that the gas-phase reaction has a significant effect not only on the deposition rate but also on the film properties.