The equation of state of Fe3S was investigated up to 200 GPa at room temperature using a diamond anvil cell. Fe3S adopts a tetragonal structure up to 200 GPa and no phase transition was observed. The fourth-order Birch-Murnaghan equation of state (EOS) was fitted to present compression data at room temperature. The elastic parameters, such as bulk modulus (K-0), its pressure derivative (K-0'), and K-0 ''(dK'/dP) were determined to be 122.4(50) GPa, 5.36(48), and -0.066(30) GPa(-1), respectively by fixing the zero pressure volume, V-0, to be 377 angstrom(3). Based on fourth-order Birch-Murnaghan EOS of Fe3S, the maximum amount of S in the inner core was estimated to be 11.4(14) at.% based on the density deficit of the inner core. (C) 2013 Elsevier B.V. All rights reserved.