The dipole-quadrupole and dipole-octopole polarizability of osmium tetroxide (OsO4) has been determined from collision-induced light-scattering experiments. Our final estimates for these properties are \A\=(84+/-5)e(2)a(0)(3)E(h)(-1) and \E\=(214+/-25)e(2)a(0)(4)E(h)(-1). We have also analyzed previous experimental data of the relative permittivity and refractivity of OsO4 to propose the electronic part of the static dipole polarizability of alpha=51.0e(2)a(0)(2)E(h)(-1). To support our findings we have performed high-level ab initio and density functional theory calculations to obtain theoretical static estimates alpha=(50.2+/-1.6)e(2)a(0)(2)E(h)(-1), A=(84+/-10)e(2)a(0)(3)E(h)(-1), and E=(-252+/-32)e(2)a(0)(4)E(h)(-1), in essential agreement with the proposed experimental values. (C) 2004 American Institute of Physics.