Abstract. The half-life of 14 O, a superallowed Fermi β + emitter, has been determined via simultaneous γ and β counting experiments at TRIUMF's Isotope Separator and Accelerator facility. Following the implantation of 14 O samples at the center of the 8π spectrometer, a γ counting measurement was performed by detecting the 2313 keV γ-rays emitted from the first excited state of the daughter 14 N using 20 high-purity germanium (HPGe) detectors. A simultaneous β counting experiment was performed using a fast plastic scintillator positioned directly behind the implantation site. The results, T 1/2 (γ) = 70.632 ± 0.094 s and T 1/2 (β) = 70.610 ± 0.030 s, are consistent with one another and, together with eight previous measurements, establish a new average for the 14 O half-life of T 1/2 = 70.619 ± 0.011 s with a reduced χ 2 of 0.99.