Nanostructured and amorphous silicon carbon nitride (SiCxNy) films have been deposited by magnetron sputtering of silicon carbide under reactive gas environment. Gas mixtures containing methane and nitrogen with various ratios were used for deposition. Auger electron spectroscopy, X-ray photoelectron spectroscopy and micro-Raman spectroscopy were employed to characterize the composition and bonding structures, while scanning electron microscopy and transmission electron microscopy were used to investigate the microstructure of the SiCxNy films. As the methane/nitrogen ratio was increased, the SiCxNy. films changed from mirror-like smooth films to column-like and ridge-like C-rich SiCxNy nanostructures. Micro-Raman studies also showed some blueshift and narrowing of the G band at higher methane concentrations, suggesting an increase in the short-range order of the graphite-like phase in the nanostructured films. The sharper geometric features of the nanostructured SiCxNy films and possibly the higher conductivity of the films led to an enhancement in field emission properties. A low turn-on field ( < 10 V mum(-1)) and high emission current density (>0.2 mA cm(-2)), as well as good temporal emission stability, have been achieved for the nanostructured SiCxNy films.