The speciation studies of oxovanadates are essential to clarify their biological activities. We surveyed the distribution of oxovanadate species in the presence of halide anions with various acid concentrations in an aqueous mixed-solvent system. The presence of chloride, bromide, and iodide anions has no effects on the appearance of polyoxovanadate species observed in 51 V NMR. Those are precedented formation of metavanadate species and decavanadates. The presence of fluoride anion during the addition of acids exhibits the strong intervention in the polyoxovanadate equilibria and we found the subsequent formation of two polyoxovanadate species by 51 V NMR observation.