Results of research on the hydrothermal precipitation of zirconium oxide from the Bureau of Mines zirconyl chloride-sulfate strip liquors indicate that nuclear-grade material can be prepared by this process. Greater than 99 pct of the zirconium value can be precipitated at 250 deg. to 260 deg. C in short reaction time without consumption of acid value of the liquor. Thus, precipitation of zirconium dioxide on a continuous basis, that is, the zirconium dioxide is precipitated in a continuous mode of operation by pumping the strip liquor through a heated pressurized reactor and recycle of the acidic liquor to the process stage are favored. The results of accompanying studies of liquid-solid separation, product washing and dewatering, product purity, and chlorination of the product are presented and discussed.