A novel modified pyrolytic graphite electrode with nano-diamond/graphite was fabricated The electro-chemical response characteristics of the modified electrode toward the epinephrine (EN) and uric acid (UA) were studied by means of cyclic and linear sweep voltammetry The structural morphology and thickness of the film was characterized by SEM technique The prepared electrode showed an excellent catalytic activity in the electrochemical oxidation of EN and UA leading to remarkable enhancements in the corresponding peak currents and lowering the peak potentials The prepared modified electrode acts as a highly sensitive sensor for simultaneous determination of EN and UA in the presence of ascorbic acid (AA) The electrode showed an excellent activity to resolving EN and UA peaks and completely eliminates the interfering effect of AA The current response of the electrode showed a linear relationship with the concentrations of EN and UA in the range of 0 01-10 mu M and 001-60 mu M respectively In these measurements a detection limit of 3 nM is resulted for both compounds This sensor exhibited very good reproducibility repeatability and sensitivity for the determination of EN in the human blood serum urine and the corresponding injecting samples Moreover the linear range and the detection limit of the determinations in the real samples remained constant in comparison with the measurements in the pure buffer solution (C) 2010 Elsevier Ltd All rights reserved