In 4SrO.7Al(2)O(3) : Eu2+ phosphor, blue Eu2+ luminescence is observed from Eu2+ on the two different strontium sites present in the lattice. The concentration quenching processes of the two inequivalent Eu2+ ions are determined respectively, and the corresponding concentration quenching mechanism is verified as dipole-dipole interaction. The critical transfer distance is calculated by using the luminescent data, which is in accordance with that obtained from the crystal structure data of the phosphor. (C) 2004 The Electrochemical Society.