Micron-thick osmium films were deposited on quartz substrates with a pulsed − 200 V bias using magnetron sputtering method. Application of ~ 100 nm Ti buffer layer resulted in successful deposition of as thick as ~ 3 μm Os films. Structure and morphology of the films were studied in terms of X-ray diffraction, scanning electron microscopy and atomic force microscopy, and their dependence on the duty-ratio was revealed. The mechanical properties of the films, namely, the Young's modulus and the hardness, were studied and discussed in comparison with the measurement of Os bulk sample. The Os film was found to be ~ 40% harder than the bulk sample due to the internal stress and the refined grains. The thickness-dependent resistivity was determined to be ρ = 13.0 + 1.74/t (μΩcm), where t is the film thickness in micron.