Thermally stable transitional alumina particulates retaining high specific surface area after calcination at 1000.degree. C. suitable for the use as catalysts or catalysts supports are produced by treating an aqueous solution containing Al.sup.3+ and optionally a doping amount of La.sup.3+ (e.g., 0.3 mol. %) with an anion-exchange resin to give a stable hydroxide sol followed by freeze drying of the sol and further thermal dehydration. The resultant stabilized transitional alumina retains high specific surface area at 1000.degree. C., and additionally stabilization is achieved at very low levels of added La.
