Gas sorption and transport properties of polymers at elevated pressures and temperatures are important for many applications. The pressure decay method is a technique, which can be used to acquire such data. Solubility and diffusion data of gases have been collected for two polymers. These polymers were polypropylene (PP) and poly vinylbutyral (PVB). Experiments with ethylene and propylene at 75°C were carried out on the PP. Experiments with argon, oxygen, and nitrogen were made using varying conditions on the PVB.