ThetitlecomplexEu(Ⅲ)(TTA)3(phen)(whereTTA=thenoyltrifluoroacetonemonoanion;phen=1,10-phenanthroline)hasbeensynthesizedinmixedsolventsofacetoneandethanol(1:1volumeratio)anditscrystalstructurehasbeendeterminedbyX-raydiffraction.Thecomplexcrystalsaretriclinic,spacegroupP1(#2)withcelldimensionsofa=1.3241(2)nm,6=1.5278(4)nm,c=0.9755(3)nm,α=92.49(2)°,β=102.57(2)°,γ=91.62(2)°,V=1.9268(8)nm3,Z=2,μ(MoKα)=18.77cm-1,Dx=1.720g/cm3.ThecoordinationgeometryofEuatomisadistortedsquareantiprism,andtheencapsulatedstructurethatcanmeetthestructuralrequirementofthetypicaleuropiumluminescentsensor.Thefluorescencespectrumsuggeststhatthecomplexisastrongphotoluminescentmaterial.