Vapor phase catalytic exchange is an important part of many hydrogen isotope separation processes. Some industrial hydrogen isotope separation processes are performed in a wide deuterium concentration range. The performance of catalysts in hydrogen-water vapor exchange reaction in the upper deuterium concentration limit is poorly investigated. The paper presents results of an investigation of catalytic activity of three catalyst types at the upper and lower limits of the deuterium concentration range. All catalyst experimental rate constants in protium-deuterium exchange demonstrated a tendency to increase with the growth of deuterium concentration. Experimental rate constants of catalysts in protium-tritium and deuterium-tritium exchange were found to remain constant. In this work the authors propose a method to be used for catalyst performance evaluation to obtain catalyst performance data for liquid phase catalytic exchange process models.