文章研究了CECE法中D₂-含氚重水同位素交换以及电解的热力学问题，即可逆分解电压和2个反应(19-1) 和(19-2)的热力学平衡条件。研究给出了H₂O， HDO， D₂O， DTO和T₂O的可逆分解电压。H₂O(0) 与T₂O(4)的可逆分解电压的相差为0.047 V，如要保留T₂O，则实际的分解电压不能大于H₂O的分解电压。同时，导出了这5种氢同位素水的平衡蒸汽压和汽化热与温度(0～100 ℃)的函数关系。从热力学来讲，反应(19-1)和(19-2)的平衡常数都很小，在静态反应中难以实现，如果在流动系统中，则能符合条件Q < K，使反应进行。电解分离氢同位素水的最大的难点是选择性差，可以探索使用光催化分离的方法。

The present work makes a contribution to thermodynamic study for the separation of tritium by CECE method from D₂-heavy water involving tritium.The reversible decomposition voltages of H₂O,HDO,D₂O,DTO and T₂O have been calculated and the difference of decomposition voltage for H₂O andT₂O is 0.047 V. Therefore,the electrolytic volt of heavy water must be less 0.047 V than that of H₂O. The functional relations of vapor pressure and vaporization heat with temperature from 0~100 ℃ for these five kinds of hydrogen-isotope water are derived. The equilibrium constants for reaction (19-1) and reaction (19-2) are also evaluated and both are quite small. Therefore,it is impossible to realize the two reactions in static system,however,it is possible to realize them in flow system. The most disadvantage for CECE method is the rather poor selectivity,the exploration is try to under way.