Graphitic substrates (plates and carbon fibre 7 mu m in diameter) have been used and characterized in order to obtain glucose sensitive electrodes. Preparation of such electrodes before enzymatic sensitization and after cleaning involves a specific electrochemical pretreatment of oxidation at +2.3 V/sce. Further covalent immobilization of glucose oxidase proceeds through a grafting between surface carboxyl group and a carbodiimide reagent Performances of enzymatic electrodes such as their stability up to two months make them well suited for further application in the biomedical field.