Tris(1, 1, 1, 2, 2, 3, 3-heptafluoro-7, 7-dimethyl-4, 6-octanedionato) europium-(Ⅲ),Eu(fod)₃, in squalane solution was usod as the stationary phase in gas-chroma-tographic investigation of the interaction between various ethers and Eu (fod)₃. It is found that the sterio hindrance plays an important role in the interaction of the saturated alkyl ethers with Eu(fod)₃.In the case of saturated alkyl ethers, the greater the sterio hindrance, the less stable aro the complexes formed and the weaker is the interaction. Whereas in the a-unsaturated alkyl ethers and aryl ethers, owing to the conjugation effect of the π-bond which excessively dcoreases the electron density around the oxygen atom, the interaction becomes less easy a,nd the eleotronic effect becomes the prinoipal factor.These results are different from tliose of the interaotion of ketonea and alcohola with Eu(fod)₃.