•Microelectrochemical characterization of the electrochemical activity on welded zones in FSW 2098-T351 Al-Cu-Li alloy.•Imaging of galvanic coupling effects and local electrochemical activity on welded zones using amperometric and potentiometric probes.•Galvanic interactions within and between the coupled welded zones were visualized by SVET and SECM analyses.•Pt and Sb/Sb2O3 probes used to map reactive sites developed on the coupled welding joint/heat affected zones (WJ/HAZ).•Spatially-resolved images of anodic and cathodic sites associated with oxygen consumption and local pH changes were monitored and studied. Localized electrochemical methods supported by surface analytical characterizations were employed to investigate galvanic coupling effects and local electrochemical activity developed along the welded zones in Friction Stir Welded 2098-T351 Al-Cu-Li alloy. The investigation was carried out in the coupled weld joint/heat affected zones (WJ/HAZ) for both, the retreating (RS) and the advancing (AS) sides. The correlation between the surface chemistry, the microstructural characteristics and the electrochemical activity of these welded areas was studied. The results showed the development of galvanic interactions within and between the WJ and HAZ regions, which were imaged using the scanning vibrating electrode technique (SVET), and scanning electrochemical microscopy (SECM). SVET analyses showed that HAZ was more susceptible to the development of anodic sites than WJ. SECM in amperometric operation mode showed that WJ coupled to HAZ exhibited higher oxygen consumption and higher cathodic activity compared to HAZ. Furthermore, SECM in potentiometric operation showed alkalinization around WJ and increased acidity in HAZ, mainly at sites of severe localized corrosion (SLC). Based on the SVET and SECM results in combination with the surface analyses, it is proposed that the microgalvanic cells formed within these welded zones are due to the presence of secondary phases in the 2098-T351 alloy and their interactions with the adjacent matrix. Display omitted