Low permeation measurements through polymer substrates is very critical and there is no definite commercial method for measuring a water vapor transmission rate of 10(-6) g/m(2)/day at 39degreesC and 95% RH at atmospheric pressure. A novel moisture permeation measurement method and model was developed qualitatively and quantitatively with the 'calcium degradation test' method. It is well known that organic light emitting device structures and other active display materials degrade in the presence of oxygen and moisture. This method would be highly suitable for assessing ultra high barrier properties of polymer substrates for organic light emitting device applications.