In this work, scanning electrochemical microscopy (SECM) measurements were employed to characterize the electrochemical activities on polished and as-received surfaces of the 2098-T351 aluminum alloy (AA2098-T351). The effects of the near surface deformed layer (NSDL) and its removal by polishing on the electrochemical activities of the alloy surface were evaluated and compared by the use of different modes of SECM. Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) were also employed to characterize the morphology of the surfaces. The surface chemistry was analyzed by X-ray photoelectron spectroscopy (XPS). The surface generation/tip collection (SG/TC) and competition modes of the SECM were used to study hydrogen gas (H 2 ) evolution and oxygen reduction reactions, respectively. H 2 evolution and oxygen reduction were more pronounced on the polished surfaces. The feedback mode of SECM was adopted to characterize the electrochemical activity of the polished surface that was previously corroded by immersion in a chloride-containing solution, in order to investigate the influence of the products formed on the active/passive domains. The precorroded surface and as-received surfaces revealed lower electrochemical activities compared with the polished surface showing that either the NSDL or corrosion products largely decreased the local electrochemical activities at the AA2098-T351 surfaces. KEYWORDS aluminum alloy, localized corrosion, SECM, surface finishing condition 1 | INTRODUCTION Aluminum alloys are commonly used in automotive and aerospace applications because of their good mechanical properties and low density.There is an increase in the demand for materials that exhibit a combination of high specific strength and corrosion resistance for industrial applications. 1,2 In order to meet this demand, new generation aluminum-lithium (Al-Li) alloys with properties superior to those of the conventionally used Al alloys are being developed for use as structural components in aircraft. [3][4][5] The AA2098 Al-Cu-Li alloy was developed as a substitute for AA2024 and AA2219. The AA2098 alloy presents low density, high mechanical resistance, high toughness, high-temperature resistance, weldability, and good response to natural aging. These properties are achieved by a carefully tailoring its chemical composition, whose main alloying elements are Cu, Li, Mg, Ag, and Zr. The addition of lithium improves the mechanical properties of the Al alloy in that for every 1 wt% of Li added to aluminum, the density of the alloy is reduced by 3%, and the Young's modulus is increased by almost 6%. 5-7 However, this element increases the susceptibility of the alloy to localized