Silicon carbide (SiC) films have been used frequently for high-frequency and powder devices but have seldom been applied as the electrode material. In this paper, we have investigated the electrochemical properties of the nanocrystalline 3C-SiC film in detail. A film with grain sizes of 5 to 20 nm shows a surface roughness of about 30 nm. The resistivity of the film is in the range of 3.5–6.2 kΩ cm. In 0.1 M H2SO4 solution, the film has a double-layer capacitance of 30–35 μF cm−2 and a potential window of 3.0 V if an absolute current density of 0.1 mA cm−2 is defined as the threshold. Its electrochemical activity was examined by using redox probes of [Ru(NH3)6]2+/3+ and [Fe(CN)6]3−/4− in aqueous solutions and by using redox probes of quinone and ferrocene in nonaqueous solutions. Diffusion-controlled, quasi-reversible electrode processes were achieved in four cases. The surface chemistry of the nanocrystalline 3C-SiC film was studied by electrochemical grafting with 4-nitrobenzenediazonium salts. The grafting was confirmed by time-of-flight secondary ion mass spectroscopy. All these results confirm that the nanocrystalline 3C-SiC film is promising for use as an electrode material.