Pressure-temperature-swing (PTS) process was comparatively investigated using one, two, or three columns packed with palladium particles. In the PTS process using the one or two columns, product was withdrawn from the system discontinuously. The deuterium enrichment ratio was lower in the one-column PTS process. In the three-column PTS process, a highly enriched product was recovered continuously. Back-filling another column and making pressure equilibrium with part of an exhaust that was slightly enriched in deuterium could enhance the enrichment ratio and recovery ratio of deuterium compared with the case of no back-filling or pressure-equilibrium operation.