[en] Uncertainties which limit the use of the ¹⁸⁷Re-¹⁸⁷Os isobaric pair as a cosmochronometer for the age of the galaxy and the universe include those of the partial half-lives of the continuum and bound-state decays of ¹⁸⁷Re. While the total half-life of the decay is well established, the partial half-life for the continuum decay is uncertain, and several previous measurements are not compatible with each other. A high-temperature quartz proportional counter has been used in this work to remeasure the continuum decay of ¹⁸⁷Re by introducing a metallo-organic rhenium compound into the counting gas. The measured beta end-point energy for the continuum decay of neutral ¹⁸⁷Re to singly ionized ¹⁸⁷Os of 2.70±0.09 keV agrees with earlier results. However, the present half-life measurement of (45±3) Gyr agrees within the quoted uncertainties only with the earlier measurement of Payne [Ph.D. thesis, University of Glasgow, 1965 (unpublished)] and Drever (private communication). The new half-life for the continuum decay and the total half-life of (43.5±1.3) Gyr, as reported by Linder et al. [Nature (London) 320, 246 (1986)] yield a branching ratio for the bound-state decay into discrete atomic states of (3±6)%. This is in agreement with the most recent calculated theoretical branching ratio of approximately 1%