Investigation of the aqueous coordination chemistry for citrate and tungsten(VI) resulted in the isolation of three new monomeric and dimeric tungsten(VI) citrate NaK 3 [W 2 O 5 (Hcit) 2 ].4H 2 O (1), (Hphen) 3 [WO 2 (H 2 cit)(Hcit)].6H 2 O (2) and K 4 [WO 3 (cit)].2H 2 O (3), (H 4 cit citric acid). The three complexes have been characterized by elemental analyses, IR and NMR spectroscopies. The IR and NMR spectra are consistent with monomeric species or a monooxo-bridged dinuclear structure as revealed by single crystal X-ray diffraction study. The dimeric anion of complex 1 contains a bent (O 2 W)O(WO 2 ) core with an angle of W Ob W 162.3(3) o . Each citrate ligand is tridentately coordinated to one tungsten atom through the α-alkoxyl, α-carboxyl, and one β-carboxyl group, making each metal atom six-coordinate and forming a mesomer with configuration of Δ S Λ R . The mononuclear tungstate 2 consists of a cis-dioxo partially protonated citrato tungstate(VI) anion and three phenanthrolinium cations. The W(VI) atom is coordinated by two acid oxo groups and two bidentate citrate ligands through α-alkoxyl and α-carboxyl groups, while the other two β-carboxyl or carboxylic groups remain free. The tungsten atom in the complex 3 forms an octahedral coordination with three fac-oxo groups and one tridentate citrate, in which the later is coordinated through the α-alkoxyl and α-carboxyl groups, and much more weakly by one of the two terminal β-carboxyl groups [2.348(4) A]. Interconversion of citrato tungstate(VI) with pH value and the molar ratio of the reactant are discussed.