Crystals of two new europium molybdates, Eu4Mo7O27 and Eu6Mo10O39, were grown in a melt of Eu2O3 ' 6.1+6.5MoO3 obtained by thermal decomposition of [Eu2(H2O)12Mo8O27] ' 6H2O or 5ring of the Eu2O3 ุ 8MoO3 mixture at 8003C for 2h in air. Repeated uses of reaction containers are e4ective in the crystallization. Eu4Mo7O27 crystallized in monoclinic, C2/c (No. 15), a โซุโฌ 23.031(1), b โซุโฌ 14.720(1), c โซุโฌ 14.4097(7) A s , โซุโฌ 105.174(2)3, V โซุโฌ 4714.8(4) A s 3 , Z โซุโฌ 8, R1 โซุโฌ 0.035, and wR2 โซุโฌ 0.064. Eu4Mo7O27 is a layer compound consisting of +MoO4,and +Mo3O11,-containing layers parallel to the bc plane and interstitial Eu atoms. Eu6Mo10O39 crystallized in monoclinic, C2/c (No. 15), a โซุโฌ 12.3008(5), b โซุโฌ 19.6596( 9), and c โซุโฌ 13.7691(4) A s , โซุโฌ 100.8934(9)3, V โซุโฌ 3269.8(2) A s 3 , Z โซุโฌ 4, R1 โซุโฌ 0.036, and wR2 โซุโฌ 0.101. The structure of Eu6Mo10O39 is constructed of three-dimensionally arranged +MoO4, and +Mo2O7, groups and Eu atoms, being closely related to the structure of Ce6Mo10O39. In both compounds, Eu atoms achieve seven-or eight-fold coordination by O atoms (< 2.7 A s ), and two EuOn polyhedra share their edges or faces with a short Eu2Eu separations ranging from 3.6297(8) to 3.7168(6) A s .