A tritium exposure apparatus has been designed and built for the purposes of generating a high-pressure tritium atmosphere at 523 K. The loading system consists of a uranium tritide storage bed, an intermediate tritium transfer chamber filled with 5A molecular sieve, and the sample exposure chamber. The loading system resides in a sealed glovebox with a nitrogen atmosphere that is continually purged through a Glovebox Clean-up System. The tritium used in each loading experiment is approximately 6000 Ci (22 TBq). The process entails transferring the tritium inventory from the uranium storage bed to the cryogenically cooled (77 K) molecular sieve chamber. The molecular sieve at liquid nitrogen temperature is capable of adsorbing tritium to densities of 290 Ci/gram at one atmosphere. At 523 K a maximum tritium pressure of 21 MPa is achieved. The loading apparatus is used to develop high-density radioactive isotope fuel for self-powered microelectronic and micromechanical devices. This paper presents the design specifics of the tritium exposure apparatus, the steps taken in generating the high-temperature, high-pressure tritium atmosphere and the performance characteristics of the apparatus. Additionally, the handling practices and equipment utilized to conduct the tests safely are presented.