Slowly cooled Cu_xFe_3-xO₄ (=0.1, 0.2) have been investigated over a temperature range from 82 to 700 K using the Mössbauer technique. X-ray diffraction shows that these have a single-phase cubic spinel structure of lattice parameters α=8.396 and 8.398Å, respectively. Since Cu ions prefer B (octahedral) sites to A (tetrahedral) sites, the ionic distribution is (Fe)_A[Fe_2-xCu_x]_BO₄. Mössbauer spectra consisted of two sets of 6-line pattern from. A site in ferric state and B site in ferrous-ferric state. Intensity ratio of B to A subspectra is 1.0 at 82 K and increases to 2.0 at 700 K with increasing temperature. After annealing the samples under vacuum at 450℃ for a half hour, x-ray diffraction patterns have the peaks of magnetite- and hematite-phase. Lattice constants of magnetite-phase are 8.395 and 8.392Å smaller than 8.396 and 8.398Å before annealing, respectively. Mössbauer spectra reveal the conventional magnetite pattern with the additional hematite pattern. Intensity ratios of B to A subspectra fur magnetite-phase become 1.9-2.0 over all temperature ranges and Cu ions are distributed over A and B sites randomly. Ratios of hematite to total intensity in Mössbauer spectra for x = 0.1 and x = 0.2 are 10 and 21%, respectively. These hematite ratios may be due to annealing under vacuum at 450℃, which transforms Cu²⁺ ionic states into Cu¹⁺. Verwey temperatures far x = 0.1 and x = 0.2 are 123±2K and 128±2K.