Résumé : We measured the neutron capture cross sections of 186,187,189Os taking for the first time their pulse height spectra for neutrons between 5 and 90 keV by means of an anti-Compton NaI(Tl) spectrometer. The neutron inelastic scattering cross section for 187Os as well as the neutron elastic scattering cross sections for 186,187Os were also observed with use of 6Li-glass scintillation detectors with a small systematic uncertainty.