For the purpose of application to volume reduction of tritiated hydrogen as gaseous waste, we carried out an experimental series of pressure swing adsorption (PSA) using a column packed with synthetic zeolite 13X (SZ-13X) at 77.4 K, where a cyclic PSA process was operated enriching D2 in a H2-D2 mixture while isolating H2 from this mixture. The result demonstrates successive reduction of a volume of this mixture with successively separating purified hydrogen volumes. It is reported here that the operational efficiency of volume reduction in the PSA process using the SZ-13X column is higher than that in the same PSA process using the same column but packed with SZ-5A. The latter is already obtained in a previous work. Comprehensively, the experimental results suggest that the PSA process is applicable to the volumetric reduction for regulating the storage inventory in a tritium waste management system.