tIn this research, new polymer of 4,4-dicyanamidobiphenyl (bpH2)-Cu(II) complex, [Cu(bp)(H2O)2]n, hasbeen synthesized and characterized by FT-IR, UV–vis spectroscopy and elemental analysis. The sphericalmorphology of Cu nanoparticles was confirmed by scanning electron microscopy (SEM) image and thetransmission electron microscopy (TEM) image showed that the particle size dimensions of Cu nanopar-ticles were about 80 nm. Thermal gravimetric analysis (TGA) results indicated that this polymer wasthermally stable. Hence, the prepared polymer was used as a modifier for the electrochemical deter-mination of dopamine (DA) and ascorbic acid (AA). Compared to the bare carbon paste electrode (CPE)and multiwall carbon paste electrode (CNTPE), bpCu modified CPE (bpCu-CPE) exhibits much higherelectrocatalytic activities toward the oxidation of dopamine and ascorbic acid with an increase in peakcurrents and a decrease in oxidation overpotentials. The effects of scan rate, concentration and pHwere also studied. Differential pulse voltammetry results show that DA and AA could be detected selec-tively and sensitively at bpCu-CPE with peak-to-peak separation of 200 mV. Relative standard deviationsfor AA and DA determinations were less than 2.5%, and the linear response ranges of the electrodewere 0.05–30.0 mol L−1for AA and DA, respectively. The calculated detection limits were 0.02 and0.04 mol L−1(S/N = 3) for AA and DA, respectively. In addition, the presented method was success-fully applied for the simultaneous determination of DA and AA in urine and blood samples with reliablerecovery.