A proton-proton collision data sample, corresponding to an integrated luminosity of 3 fb−1 collected by LHCb at s√=7 and 8 TeV, is used to reconstruct 63±9 Ω−b→Ω0cπ−, Ω0c→pK−K−π+ decays. Using the Ξ−b→Ξ0cπ−, Ξ0c→pK−K−π+ decay mode for calibration, the lifetime ratio and absolute lifetime of the Ω−b baryon are measured to be τΩ−bτΞ−bτΩ−b=1.11±0.16±0.03,=1.78±0.26±0.05±0.06 ps, where the uncertainties are statistical, systematic and from the calibration mode (for τΩ−b only). A measurement is also made of the mass difference, mΩ−b−mΞ−b, and the corresponding Ω−b mass, which yields mΩ−b−mΞ−bmΩ−b=247.4±3.2±0.5 MeV/c2,=6045.1±3.2±0.5±0.6 MeV/c2. These results are consistent with previous measurements.