The effects of several polyhydroxy compounds ( glucose, fructose, gumsugar, galactose, trehalose, dextran, xylose, PEG200, glycerin) and surfactant ( dioctyl sulfosuccinate sodium salt, AOT) on the catalytic activity and thermal stability of chloroperoxidase (CPO) in aqueous systems were investigated at various temperatures. A 25% superactivity was found in AOT solutions at 25 degrees C, and it could be maintained during the 882 h. PEG200 and glycerin were proven to be the most efficient stabilizer for CPO in temperatures ranging from 25 to 60 degrees C. Trehalose is more helpful than other sugars for extended storage of CPO. These results are promising in view of industrial applications of this versatile biological catalyst. The protective mechanism of various additives on CPO was discussed.