The synthesis and characterization of the first water-stable monomeric monooxovanadium(V)) complexes are reported. These complexes are chelated by novel multidentate N/O donor ligands. The ligands were synthesized by reduction of the Schiff base precursors H(2)sal(2)en, N,N’-bis(salicylidene)ethylenediamine, and H(2)shed, N-salicylidene-N’-(2-hydroxyethyl)ethylenediamine, using sodium borohydride to produce H(2)sal(2)enr, N,N’-bis-((o-hydroxyphenyl)methyl) ethylenediamine, and H(2)shedr, N-((o-hydroxyphenyl)methyl)-N’-(2-hydroxyethyl)-ethylenediamine, which are stable to hydrolysis at the imine linkage. Alkylation of H(2)shed followed by reduction leads to the higher denticity, hydrolytically stable ligands H(3)heshedr, N-((o-hydroxyphenyl)methyl)-N’-bis(2-hydroxyethyl)ethylenediamine, and H(3)salshedr, N-(2-hydroxyethyl)-N,N’-bis((o-hydroxyphenyl)methyl)ethylene- diamine. Similarly, alkylation of H(2)sal(2)enr with 2-(bromomethyl)phenyl acetate produces H(2)sal(3)enr, N,N,N’-tris((o-hydroxyphenyl)methyl)ethylenediamine. These ligands have been developed in order to solve the problem of imine hydrolysis that is often associated with vanadium Schiff base complexes. Reaction with sodium vanadate or triethyl vanadate gives a series of dioxo- and monooxovanadium(V) complexes. The compound [VO2(Hshedr)](2),, 2, is a water-soluble and water-stable analogue of [VO2(Hshed)](2), 1, whose X-ray structure reveals that it is isostructural with 1. Complexation of vanadium by the higher denticity ligands leads to monooxovanadium(V) compounds with the general composition seen in the X-ray structure of VO(salshedr), 4. The complexes VO-(sal(3)enr), 5, and 4are stable in mixed organic/aqueous solution and in the presence of hydrogen peroxide. In contrast, VO(heshedr), 3, will convert to VO2(H(2)heshedr), 6, with trace water.