Tritium production-rate (TPR) distributions were measured in a Li2O slab assembly using the FNS. The size of assembly was 31.5 cm in equivalent radius and 61.0 cm in thickness. Enriched 6Li and 7Li sintered pellets of Li2O were adopted to measure the TPRs of 6Li and 7Li, separately. After irradiated pellets were treated chemically, tritium produced in the pellets was measured by a liquid scintillation counting system. Measured TPR distributions have been analyzed by using the three transport codes, DOT3.5, MORSE-DD and BERMUDA-2DN with ENDF/B-4 and JENDL-3PR1 nuclear data files. The JENDL-3PR1 improves the accuracy of calculated TPR very well for both 6Li and 7Li.