Using X-ray absorption fine structure spectroscopy, both EXAFS and XANES, the cation distributions in NiFe2O4 particles dispersed in a corrosion product deposit layer have been studied. The specimen was obtained from a selected fuel rod used in a commercial boiling water reactor plant. EXAFS data allowed the quantitative determination of specific site distributions for all transition metal cations in Ni-ferrite deposits. The results show that the analyzed NiFe2O4 particles do not have a totally inverted spinel structure. The relative occupancy of iron and nickel cations in the tetrahedral and octahedral sites of the spinel lattice is determined from the measured data. (C) 2010 Elsevier B.V. All rights reserved.