Yttrium is involved as oxide in a variety of advanced materials. Hydrolysis of its most common alkoxide, yttrium oxoisopropoxide Y5O(OiPr)13 , is difficult to control as a result of the high electropositivity of the metal. Functional alcohols such as 2-methoxyethanol and acetylacetone have thus been used as modifiers. These tailored precursors have been fully characterized (single crystal X-Ray diffraction, IR, NMR. ). The tendency of methoxyethanol to act as a bridging ligand and to stabilize high oligomers - Y(OC2H4OMe)3 is a decamer - gives some insight into its behavior as “network builder”. The unexpected cleavage of acetylacetone offers a route to an interesting acetatoacetylacetonate derivative, Y2(OAc)2(acac)4(H2O)2 , but also suggest that this classical “modifier” could be affected by the hydrolysis-polycondensation reactions of the metallic species during the sol-gel process. Comparison of the hydrolysis behavior of the different precursors was performed.