The equations for predicting the degrees of separation of H-2, HD and D-2 from H-D gas mixture by thermal diffusion in countercurrent-flow concentric-tube Frazier schemes of single and multiple columns, have been derived. The equations for predicting the recovery of deuterium (D) in HD and D-2 were then obtained with the use of the atomic weight ratio. The degrees of separation, as well as separation factors, for deuterium recovery in the cryogenic-wall thermal diffusion devices were estimated, with the use of the experimental data obtained by Arita et al., 1998 and with the transport coefficients correlated in the previous work. Considerable improvement in deuterium recovery is achievable if a Frazier scheme with multiple columns is employed, instead of using the single-column device, either with the same column height, or with the same total sum of column heights, especially for the operation under larger volume flow rate and/or higher operating pressure. Further, countercurrent-flow operation is better than concurrent-flow operation in multi-column devices. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.