A mathematical simulation procedure is developed for a single cryogenic distillation column with a feedback stream and a catalytic equilibrator used for protium-tritium (HT) separation. Large errors in calculation of mole fractions of the HT in the two products may occur unless special care is taken. Errors are minimized here by solving a single-variable nonlinear equation using the Newton-Raphson method. Parametric investigations of interest for column design and operation are also presented. One result is that the sidestream location is found to strongly affect column performance, and the optimum location depends strongly on the external feed composition. Further, as the mole percentage of HT in the external feed increases, the flow rate of the sidestream must be increased. Finally the effect of thermodynamic properties of the isotopes and of the decay heat of tritium on static column behavior are examined. Differences in the latent heat of vaporization among the three molecular species (H2, HT, and T2) are found to be significant. It appears that consideration of the decay heat of tritium and of the nonideality of the H2-HT-T2 solution is necessary to accurately predict the tritium concentration in the top product of high purity protium, a key output parameter. The usual assumption of equal molal heats and equal molal overflows within the column can lead to error in the reboiler load exceeding +250%.