The electrochemical behavior of guanine at a CCO Np modified glassy carbon electrode (CCO/MGCE) was investigated by voltametric technique. The CCO Np was synthesized by coprecipitation method and characterized by X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). Guanine is oxidized at CCO Np modified GCE at a working potential of 0.7049V. Oxidation peak appeared at pH 7.0 supportive electrolyte concentration 0.2 M phosphate buffer solution (PBS). Evaluated the limit of detection and limit of quantification by varying the concentration of guanine. pH Studies were carried out and examined the protons and electron ratio involved in the process by using cyclic voltammetry (CV).