Experimental study for separation of hydrogen isotopes has been performed by using a ‘cryogenic-wall’ thermal diffusion column. The separation experiments were carried out with H-D system under total reflux and continuous feed operation mode. The dependence of the separation factor on the column pressure were examined for both experiments. In the total reflux experiments, the maximum separation factor of the ‘cryogenic-wall’ column was about 12.4 times larger than for the ‘water cooled-wall’. The effect of the feed flow rate on the separation factor and on the optimum pressure was examined in the continuous feed experiments. As the feed flow rate increased, the separation factor decrease appreciably, and the optimum pressure shift progressively to higher region.