Chloroperoxidase from Caldariomyces fumago (CPO, EC 1.11.1.10) is one of the most interesting enzymes from the group of heme peroxidases and has been extensively applied in synthetic processes. Nevertheless, the practical application of CPO is limited due to its very low operational stability, especially in the presence of peroxidative compounds. For this reason, effect of chemical modifications of CPO in the stability of the enzyme was studied. Side-chain selective modifications of amino groups of Lys residues, and carboxyl groups of Asp and Glu residues, as well as crosslinking and periodate oxidation of sugar moiety were carried out. The stability of modified CPOs was evaluated at elevated pH and temperature, and in the presence of tert-butyl hydroperoxide. Effect of modification of CPO on the performance of the reaction of Cbz-ethanolamine oxidation was studied as well. Those modifications that involved carboxyl groups via carbodiimide coupled method and the periodate oxidation of the sugar moiety produced better catalysts than native CPO in terms of stability and activity at elevated pH values and temperatures. (C) 2014 Elsevier Ltd. All rights reserved.