The effect of titanate, zirconate, and zircoaluminate coupling agents on the viscosity of zirconia‐polypropylene injection molding blends was investigated. The zircoaluminate did not influence viscosity while the two former additives effected a considerable reduction. The titanate coupling agent also reduced the viscosity of the polymer in the absence of ceramic powder, and was more efficient in this respect, as a flow modifier than dioctyl phthalate. A comparable effect on the ceramic suspension was obtained by adding a species similar in molecular structure to the titanate coupling agent but without coupling ability.