A pair of separation column packed with different hydrogen absorption materials (Pd/k and 4A molecular sieves) respectively, whose hydrogen isotopic effect is opposite, is used in Thermal Cycling Absorption Process (TCAP), and its result of hydrogen isotopes separation is better than the traditional TCAP. A dynamic simulation method for the pair of column TCAP system is developed. For a certain percentage of binary gas mixtures of hydrogen isotopes (H-2 and D-2) injected into the twin columns system, from simulation results, it can be obtained the binary gas concentration distribution in the two columns after a different number of cycles. Furthermore, the separation process can be optimized. Moreover, it can be seen that the hydrogen isotopes separation effect of twin columns TCAP is almost twice that of the traditional TCAP. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.