Microscopic aspects of electrochemical reactions in a B10 Cu-Ni alloy/2205 duplex stainless steel (DSS) galvanic couple immersed in NaCl solution were investigated by electrochemical noise (EN) technique, scanning kelvin probe force microscopy (SKPFM), scanning vibrating electrode technology (SVET) as well as by scanning electron microscopy (SEM) method. Wavelet analysis by EN technique and microscopic characterization showed that the galvanic corrosion process can be divided into five detail stages. SKPFM and SEM observations revealed that the B10 Cu-Ni alloy/2205 DSS is a small-scale B10/ferrite/austenitic galvanic corrosion system that reduces the resistance of 2205 DSS to pitting attack. •Galvanic corrosion of Cu-Ni alloy/2205 DSS couple was analyzed.•Pitting corrosion was observed on the surface of cathodic 2205 DSS in the galvanic system.•The galvanic corrosion process can be divided into five stages by wavelet analysis.•More accurate corrosion mechanism can be revealed by EN analysis.