Abstract: The polarographic and voltammetric behaviour of Cu(Ⅱ) xanthosine complex has been studied. A new sharp reduction peak is yielded at the potential of -0.14 V(vs, Ag/AgCl). The conc. of Cu(Ⅱ) is proportional to peak current of NPP in the range of 1×10 -6 ～1×10 -4 mol/L when the conc. of xanthosine is 1×10 -4 mol/L. It is indicated that the current has adsorption character. The mechanism of the electrode reaction was deduced and the ratio of the complex is Cu(Ⅱ) ∶ xanthosine=1∶1.