Four new kinds of europium complexes were synthesized and their mechanoluminescent properties were investigated. Out of the four, only europium tris(2-thenoyltrifluoroacetone) phenanthroline (Eu(TTA)(3)(phen)) exhibited intense mechanoluminescence. Its spectra were measured and found to be essentially the same as that of the photoluminescence, indicating an identical emitting species. The excitation mechanisms of mechanoluminescence are also discussed.