An enhanced resistance to thermal denaturation was investigated for enzymes immobilized within hydrophobic semi‐solid matrices compared with both free enzymes and polymer‐entrapped enzymes. The bioelectrodes based on the immobilization of glucose oxidase, lactate oxidase, alcohol oxidase, polyphenol oxidase, peroxidase and L‐amino acid oxidase within a carbon‐paste matrix were constructed to examine their thermal stabilitiy at 60 °C or 80 °C. The rhodium/glucose oxidase‐containing carbon‐paste electrode was found to offer a remarkable stability when incubated at 60 °C over a long period of 4 months, with only a decrease of approx. 15% in activity. The comparative studies suggest that thermal stabilization established by this enzyme‐immobilization procedure varies with the enzyme’s inherent stability, the incubation temperature and the immobilizing reagent, such as pasting liquid.