A very simple and fast immobilization technique based on ion exchange was investigated to improve the thermal stability of acid phosphatase from wheat germ and potato. Immobilization was not efficient for the DEAE-sepharose, and MANAE-agarose supports. On the other hand, Toyopearl DEAE-650s proved to be a promising support, with immobilization yield above 95% and recovery of activity above 85% for both enzymes. A second step was introduced in the immobilization protocol to improve the thermal stability of these biocatalysts. For this, oxidation and reduction of glycosidic chains of acid phosphatase were carried out, allowing the formation of aldehyde groups and subsequent interaction with the amine groups to further stabilize the different forms (free and immobilized). Both biocatalysts showed residual activity after 1 hour of inactivation at the temperature of 60 oC, a fact not observed for the free enzyme. The wheat germ acid phosphatase derivative was the most stable, with residual activity of 66.7% for the only immobilized derivative and 76.2% for the oxidized/reduced derivative. Also, the derivatives prepared by ion exchange adsorption on Toyopearl (TOYO), followed by oxidation/reduction and intramolecular crosslinking, were approximately 15 and 41 times more stable than the free enzyme from wheat germ.