A PLATINUM OXIDE CATALYST, WHICH HAS THE UNIQUE PROPERTY OF BECOMING HIGHLY FLOCCULATED IN THE REDUCED STATE, IS EMPLOYED IN AN IMPROVED METHOD FOR PREPARING STABLE URANIUM-CONTAINING SQUASOLS FROM A URANIUM (V)-CONTAINING FEED SOLUTION WHICH IS CATALYTICALLY REDUCED BY HYDROGEN TO A URANIUM (V)-CONTAINING SOLUTION IN A FLOW-THROUGH REDUCTOR VESSEL. THE REDUCED PLATINUM OXIDE CATALYST IS READILY RETAINED IN THE REDUCTOR VESSEL ON A PORPUS FILETER AND THE URANIUM (IV)-CONTAINING SOLUTION IS THEN PROCESSED INTO A STABLE URANIUM-CONTAINING AQUASOL AND CALCINED URANIUM DIOXIDE MICROSPHERES BY KNOWN SOL-GEL PROCESSES.