The electronic structures of (Fe,Mn)3O4 spinel oxides have been investigated by employing soft-x-ray absorption spectroscopy (XAS) and soft x-ray magnetic circular dichroism (XMCD). We have determined the valence states as well as the occupation sites of Mn and Fe ions in Fe0.9Mn2.1O4 and MnFe2O4. Fe0.9Mn2.1O4 is found to be close to the inverse spinel (the inversion parameter y≈0.85), while MnFe2O4 is close to the normal spinel (y≈0.2). In Fe0.9Mn2.1O4, Fe ions are mainly trivalent and the majority of Fe3+ ions occupy the octahedral B sites, while Mn ions are mixed-valent with approximately 45% MnA2+ at the tetrahedral A sites and 55% MnB3+ ions at the octahedral B sites. In MnFe2O4, Mn ions are mainly divalent and the majority of Mn2+ ions occupy the tetrahedral A sites, while Fe ions are mainly trivalent and the majority of Fe3+ ions occupy the octahedral B sites.