The first observation of emission of electronically-excited states of the divalent Eu2+⁎ ion in the new chemiluminescent system EuCl3·6H2O-Bui2AlH-O2 and the energy transfer from Eu2+⁎ ion to the trivalent ion, Tb3+

► The first chemiluminescence of divalent lanthanide Eu2+ in liquid-phase reaction was found. ► Eu2+⁎ is generated and emitted at λmax=465 nm in EuCl3·6H2O-THF-Bui2AlH-O2 the system. ► Eu2+⁎ is formed during energy transfer from triplet C3H7С(H)O⁎ generated in Bui2AlH oxidation by O2. ► For the first time was established of energy transfer from Eu2+⁎ to Tb3+ in solution was established.