Deuterium and tritium exchanges were performed on the aromatic groups of polystyrene using DCl or TCl and TiCl4. Up to 5 deuterium atoms per monomer unit could be placed on the aromatic groups depending upon time, DCI pressure, and TiCl4 concentration. Tritiated polystyrene mixed with zinc sulfide phosphor produced 1.06 Cd/m2 of luminance.