Research equipment has been designed, fabricated, and evaluated for determining the conversion rate of tritium gas to tritiated water for initial tritium gas concentrations ranging from the maximum permissible concentration of tritium gas for occupational exposures of 7.4 x 10/sup -5/ TBq/m/sup 3/ to 3.7 x 10/sup 2/ TBq/m/sup 3/. The equipment includes a vacuum system coupled to a gas handling system for preparing up to 15 reaction vessels having identical tritium gas concentrations. Measured concentrations in 4 or 5 prepared flasks were within 1.6% of their mean. Measured concentrations in all 5 flasks were within 8% of the mean. Good control of the tritium concentration was also achieved. A system was required for sampling tritiated water and tritium gas. Efficient collection of HTO was desired and reproducible collection of HTO and HT were essential. Collection efficiencies for tritiated water of at least 99% were obtained reproducibly. Collection efficiencies of tritium gas were also 99% or greater and reproducible.