Peroxidase (POD) activity was measured in peaches, carrots and potatoes after blanching treatments at different constant temperatures. Two isoenzymes exist, one bound and one soluble. The bound form can be converted into the soluble form by a temperature-dependent conversion reaction. Both forms are susceptible to heat denaturation. However; the conversion precedes the denaturation of the bound form. Neat denaturation of the enzymes could be described using an exponential decay first order reaction). The temperature dependence of all reaction rates could be described by Arrhenius＇ law The simultaneous analysis of bound and soluble POD in peaches explained 96.4% of the observed variance. The analysis for carrots and potatoes on bound POD alone, yielded a ＇percentage variance accounted for＇ of 94.5 and 70%, respectively.