Covalent immobilization of pure lipases A and B from Candida rugosa on agarose and silica is described. the immobilization increases the half-life of the biocatalysts (t1/2 approximate to 5 h) with respect to the native pure lipases (t1/2 approximate to 0.28 h). The percentage immobilization of lipases A and B is similar in both supports (33-40%). The remaining activity of the biocatalysts immobilized on agarose (70-75%) is greater than that of the enzymatic derivatives immobilized on SiO2 (40-50%). The surface area and the hydrophobic/hydrophilic properties of the support control the lipase activity of these derivatives. The thermal stability of the immobilized lipase A derivatives is greater than that of lipase B derivatives. The nature of the support influences the thermal deactivation profile of the immobilized derivatives. The immobilization in agarose (hydrophilic support) gives biocatalysts that show a greater initial specific reaction rate than the biocatalysts immobilized in SiO2 (hydrophobic support) using the hydrolysis of the esters of (R) or (S) 2-chloropropanoic and of (R,S) 2-phenylpropanoic acids as the reaction test. The enzymatic derivatives are active for at least 196 h under hydrolysis conditions. The stereospecificity of the native and the immobilized enzymes is the same.