Metal-Oxide-Metal thin film diodes have been fabricated on the glass substrates by conventional vacuum evaporation method, and the electrical properties, primarily current-voltage characteristics of diodes, have been discussed in the light of various conduction theories presented so far. The experimental results were ploted in the different figures according to the assumed theory, and the characteristic coefficients peculior to these theories were estimated from the function dependence of current (I) upon voltage (V), temperature (T) and oxide film thickness (d).