The induced molecular environment of a spacecraft and the contamination of instruments and surfaces are largely dependent on the molecular outgassing of its materials. The materials are selected in accordance with the criteria that when a sample of that material is held in vacuum for 24 hours at 125°C, it will not lose more than 1 percent of its mass nor will it deposit more than .1 percent of its mass on a 25°C collecting surface. Many materials have been tested for these criteria and other spacecraft materials are being routinely tested. The results are readily available in the literature. Unfortunately, the criteria and the test results neither indicate mass losses at other temperatures, nor do they provide data on mass loss as a function of time. Both of these parameters are needed to evaluate the induced environment and to estimate surface degradations. In this paper a large number of normalized plots of material mass losses versus time have been prepared based on theoretical and experimental behavior of materials under vacuum. They cover a range of temperatures up to 125°C and outgassing activation energies up to 40 kcal/mole. The plots are intended to provide a description of the outgassing kinetics of the material given the results of the criteria test and some additional data from the same type of test carried out at other temperatures and/or for different testing time. This approach can add to the present characterization of materials and avoid, in many cases, the costly long term tests which measure continuously the mass loss of a sample at a specific temperature.