A bismuth-coated carbon fiber microelectrode was prepared using cyclic voltammetry (CV). An analytical application was performed for the copper analysis with Square Wave Stripping Voltammetry (SWSV). Gallic acid n-propyl ester (PG) was used for the complex formation with a copper ion, and electrochemical measurements were performed with a pre-amplifier of a low-current module for nano am per detection. The effects of various parameters on the response were optimized. Analytical working ranges of $0.03-25.9;{mu}gl^{-1}$ and $0-25'mgl^{-1}$ Cu(II) were obtained. The relative standard deviation at $13;mgl^{-1}$ Cu was 0.9% (n = 12) in optimum conditions. The detection limit was found to have been $0.019;{mu}gl^{-1}$, with a 30-sec accumulation time. The developed methods were applied to a copper assay in water samples.