The existence of tritium as a product of fission, first reported by Albenesius, (1) has been verified. A ratio of 1·25 ± 0·15 × 10 4 fissions per atom of tritium was found for the thermal neutron-induced fission of 235U. Tritium was converted to water in a closed system and its activity measured by liquid scintillation techniques. The number of fissions was determined by assay of the 0·537 MeV γ-ray of 140Ba.