AbstractThe luminescence spectra and radiative lifetimes of a series of d3 and d6 double complex compounds with bipyridine (bip), phenanthroline (phen), ammonia and ethylenediamine (en) ligands in the cations and chloride, cyanide, thiocyanide and oxalate (ox) ligands in the anions have been investigated at temperatures down to 2 K. Although energy transfer between the component ions is predicted from the Förster and Dexter theory to be effective due to the finite overlap of the donor emission and the acceptor absorption spectra, no emission could be detected for most of the double complexes. Only [Ru(bip)3]tr-[Cr(NH3)2(NCS)4]2, [Ru(bip)3][PtCl6] and [Cr(d4-en)3] [Rh(SCN)6] exhibit characteristic luminescence spectra which in part are enhanced compared to their component emissions. For rationalizing the results, radiationless deactivation by various decay channels which compete with the energy transfer mechanism must be considered.