In this article, we focused on the comprehension of the surface reactivity of layered beta(III)-cobalt oxyhydroxide, beta(III)-CoOOH, by implementing a multiscale study associating both experimental, surface characterization by X-ray photo-emission spectroscopy (XPS) and scanning electron microscopy and first-principles calculations. The surface reactivity and the chemical properties of the surface are key factors in the charge-storage mechanism, and beta(III)-CoOOH presents interesting characteristics to be used as pseudo-capacitive electrode materials in supercapacitors thanks to its large surface specific area (similar to 100 m(2)/g(s)) and its high electronic conductivity (10(-3) to 1 S cm(-1)). The surface reactivity (basic and redox character) of the synthesized compounds, which consists in aggregates of particles with 60-100 nm length, has been explored from the adsorption of SO2 molecules followed by XPS analyses. A kinetic study of the reactivity allowed us to identify three steps in the adsorption mechanism of our beta(III)-CoOOH samples. The coupling of XPS and computational results allows us to establish a link between the surface reactivity in the identified domains, the formation of sulfate and sulfite species, and the cobalt Co3+ and Co4+ species of the active sites along with the underlying electronic processes.