Nano-crystalline, zirconium oxide/oxyhydroxide particulates were produced using a novel, continuous, flow-through hydrothermal technology developed at the Pacific Northwest National Laboratory. Homogeneous aqueous solutions containing ZrO(NO 3)2 and urea were pumped at pressures of 6000-8000 psi through a heated stainless steel reaction tube at 340-350°C. Flow at pressure was maintained using a nozzle at the down-stream end of the reaction tube. In this process, termed Rapid Thermal Decomposition of precursors in Solution (RTDS), the formation of zirconium oxide/oxyhydroxide nano-crystals (diameters of generally less than 15-nm) occurred during the solution's brief residence time (<15 seconds) in the reaction tube, yielding aqueous slurries of agglomerated particulates. Powders were separated from these slurries, washed, then dried. RTDS powder prepared from 0.3M ZrO(NO3)2 and 0.6M urea were mixed with binder and formed into pellets using a commercial screw extruder. These extrudates were subsequently sintered at 500°C, yielding zirconia catalyst support pellets with a measured surface area of 113 m2/g. After application of 3% ruthenium metal to the sintered RTDS zirconia extrudates, the resulting catalyst was evaluated for catalytic activity using the hydrothermal hydrogenation of the sugar xylose to xylitol as a model reaction. After 3 hours at 140°C, the RTDS catalyst exhibited useful activity with 92% conversion and 66% selectivity to xylitol formation.