radioactivity Standard Reference Materi-

als (SRMs), we have performed a compre-hensive review and critical evaluation of the half-life of tritium (hydrogen-3). Twenty three experimentally-determined values of the half-life of tritium, reported between 1936 and 2000, were found. Six of these values were updated by later val-ues. Two values were limits. Two values were deemed to be outliers. The 13 remain-ing values were evaluated in several ways. The results are compared with the results of other recent evaluations and all are found to be in good agreement. Our fi-nal recommended value for the half-life of tritium is the average of the adopted val-ues from the four most recent evalua-tions, (4500 8) d, where 8 d corresponds to one standard uncertainty. Key words: evaluation; half-life; hydro-gen-3; review; tritium