Gas chromatography has been used as one of the practical methods for separation and enrichment of hydrogen isotopes in fields of operation or handling a hydrogen isotope facility. Chromatographic separation experiments of a mixture of hydrogen isotopes including with hydrogen(H₂), hydrogen deutride(HD) and deuterium(D₂) were carried out. The complete separation of hydrogen isotopes was observed with an alumina adsorbent partially deactivated by coating with 10% manganese chloride(Mn-Cl₂), which could be available for the practical applications of the hydrogen isotope separation and enrichment.