The crystal structure of CuCrSe₂ in the temperature range 25 - 1000 °C was studied by synchrotron X-ray diffraction. It was found that heating leads to the decomposition of stoichiometric CuCrSe₂ into two phases of composition CuCr₂Se₄ and Cu_1+xCrSe₂ with increased Cu content. It was found that copper enrichment of CuCrSe₂ during heating occurs up to the temperature of 800 °C and the limiting composition is close to the compound Cu₄Cr₃Se₆. It was found that heating equalizes the copper distribution at the α- and β-tetrahedrally coordinated chalcogen positions, but full equality of their occupancy at temperatures up to 1000 °C was not achieved. The low temperature limit of CuCr₂Se₄ excretion was established to be approximately 300 °C and the decomposition temperature of CuCr₂Se₄ to be approximately 1050 °C.