The green fluorescence of the following phosphors is reported: , , , , and . Their crystal structures are based on the rocksalt lattice. It is found that for increasing lithium content of the host lattice the position of the maximum of the emission band shifts to shorter wavelengths and the quantum efficiency increases. This relation is discussed. Concentration quenching occurs at low activator concentration. with regular octahedra emits also in the green. For some other compounds red emission was found. Green uranium emission is assigned to groups and uranyl groups, red emission to groups. It is shown that this assignment is consistent with the structural data for a large number of uranium‐activated oxides. Energy transfer was observed between the uranium center and Eu3+. Addition of Cr3+ or Rh3+ quenches the uranium fluorescence drastically.