A correlation between film structures and the width of the potential windows defined by the dihydrogen and dioxygen evolutions in aqueous media at nitrogen-doped amorphous carbon thin film electrodes prepared using a filtered cathodic vacuum arc system is reported. A range of film structures were obtained by changing the nitrogen mass flow rate during deposition, and the film structures were determined using electron energy-loss spectroscopy. For the film electrodes, the width of the potential windows in 0.1 M NaOH and in 0.1 M H₂SO₄ at a current density of 100 μA/cm² exceed those for glassy carbon electrodes, and increase with an increase in the sp³C fraction in the a-C:N materials. A film electrode with a rich sp²C content, has a lower electrical resistance, but still possesses a relatively large potential window. These features combined allow the materials to be tailored for particular electroanalysis.