Hydrogen isotope gases expelled from nuclear fusion reactors can be purified by a process combining catalytic deoxygenation and cryogenic adsorption (77.4 K). In the present work, a novel purification process design is proposed. The experimental result shows that the oxygen volume fraction of the purified hydrogen isotopes is below 0.1 x 10(-6) with the nitrogen volume fraction less than 1 x 10(-6). And it was discovered that the waste amount of hydrogen isotopes after purification is only 100-300 ppm which occupies just 10-30% of the amount of nitrogen impurity through the theory calculation. Therefore, the impurity content of hydrogen isotopes is removed sufficiently by the combined process and the proposed process for purification of the exhaust gases expelled from nuclear fusion reactors can be used as an alternative to the traditional method. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.