We report characterization of highly conducting and amorphous osmium dioxide thin films. The films deposited by glow discharge of osmium tetroxide showed no peaks in X-ray diffraction and homogeneous distribution of osmium and oxygen atoms in depth profile by Auger electron spectroscopy. The amorphous Os-O films were highly conducting (<5 X 10(-3) Ohm cm), and the conductivity was almost temperature independent. High-resolution X-ray photoelectron spectroscopy revealed that the films were osmium dioxide (OsO2). Argon ion bombardment of the film reduced the Os4+ to metal OsO via a transition state (Os1.6+).