Ti(NEt2)4 and Zr(NEt2)4 were used as single-source precursors to deposit titanium and zirconium carbonitride thin films on Si(100) and glass substrates at temperatures 673-923 K by low-pressure chemical vapor deposition. The thin films were analyzed by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, wavelength dispersive spectroscopy, and infrared spectroscopy. The films deposited at high temperatures crystallized into cubic structures as shown by X-ray diffraction. The nitrogen-to-metal ratios were close to unity in most cases while the carbon-to-metal ratios decreased with increasing deposition temperature. At deposition temperatures below 773 K, hydrocarbon stretchings were observed by IR. Attempts to decrease carbon levels in thin films by adding H2 into the carrier gas showed opposite effects.