The valence and spin states of MnFe(2)O(4) spinel oxide have been investigated by employing soft x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD). The measured Mn 2p and Fe 2p XAS spectra indicate that Mn and Fe ions are nearly divalent (Mn(2+)) and trivalent (Fe(3+)), respectively. Our XAS and XMCD spectra for MnFe(2)O(4) do not show clear evidence of mixed-valent states but provide evidence for the inversion of both Mn and Fe ions, with T(d)/O(h)similar to 0.8/0.2 for Mn ions and T(d)/O(h)similar to 0.1/0.9 for Fe ions, respectively. Based on our data, MnFe(2)O(4) can be described either by the single-valence states of (Mn(0.8)(2+)Fe(0.2)(3+))(A)[Fe(1.8)(3+)Mn(0.2)(2+)](B)O(4) or by the mixed-valence states of (Mn(0.8)(2+)Fe(0.2)(3+))(A)[Fe(1.6)(3+)Fe(0.2)(2+)Mn(0.2)(3+)](B)O(4).