This paper discusses how the luminescence of the U6+ ion in oxides is influenced by the crystal structure and the chemical composition of the host lattice. The vibrational fine structure of the emission band, the decay time, and the thermal quenching temperature of the luminescence are the properties which we concentrate on. Starting point of the discussion is the perfectly cubic group, the emission of which corresponds to a zero‐phonon magnetic‐dipole transition followed by mainly one‐photon vibronics. The influence of symmetry lowering on this emission is described. This influence becomes of striking importance if the U6+ ion is introduced in host lattices containing edge‐sharing groups. Finally some general aspects of the vibrational fine structure, in particular the length of the progression in , are discussed. The strong dependence of the thermal quenching temperature of the U6+ luminescence on the host lattice can be explained using a configurational‐coordinate diagram with three parabolas.