Samples of ultrahigh molecular weight polyethylene (UHMW-PE), polytetrafluoroethylene (PTFE), and the polyimide Vespel[registered trademark] were exposed to tritium gas in closed containers initially at 101 kPa (1 atmosphere) pressure and ambient temperature for various times up to 2.3 years. Tritium exposure effects on the samples were characterized by dynamic mechanical analysis (DMA) and radiolysis products were characterized by measuring the total final pressure and composition in the exposure containers at the end of exposure period.