Poly(vinyl alcohol) (PVA) gels favorably with boron oxide (B2O3) in aqueous slurries of BaTiO3, resulting in a dilatant rheology, but the gelation and dilatancy can be efficiently reduced by the use of hydroxylated BaTiO3. The degelation effect caused by the use of hydroxylated BaTiO3 was studied, and the corresponding degelation mechanisms were clarified. Interestingly, the hydroxylated BaTiO3 interacts better than the as-received form with PVA and B2O3, and the hydroxylated form is more chemically stable and less soluble in the aqueous slurry. Based on these specific properties of hydroxylated BaTiO3, especially its good chemical stability, the free concentrations of PVA and −B(OH)4 in the aqueous slurry are efficiently diminished. The decreased free concentrations of PVA and B2O3 facilitate the reduction of the gelation opportunity between them, leading to a great improvement in the rheological behavior of the aqueous slurries.