The electrical and optical characteristics of an overvoltage nanosecond discharge (OND) between the tungsten electrodes in oxygen (p = 101, 13.3 kPa) are presented. The formation of clusters and nanoparticles of tungsten oxide within the OND plasma is occurred during the introduction of tungsten vapour into the discharge gap, resulting from microexplosions of natural inhomogeneities on the electrode surface within the strong electric-discharge field, along with the formation of ectons. This creates the conditions for synthesizing thin films of tungsten oxide (WO₃), which could be deposited onto a glass substrate placed near the discharge gap. Oscillograms of the voltage and current pulses, pulse power and energy contributions to the plasma per discharge pulse, as well as the spectral characteristics of the OND, are studied. The primary excited components of the plasma of a tungsten−oxygen vapour–gas mixture are identified. Micro-Raman spectroscopy of the synthesized films reveals that they consist of tungsten oxide (WO₃).