Self-assembled monolayers (SAMs) have grown into an extremely active research field (A. Ulman, An Introduction to Ultrathin Organic Films From Langmuir-Blodgett to Self-Assembly, Academic Press, San Diego, CA, 1991, Chapter 3) [1]. However, the development of valuable and practicable industrial technologies from this research is still in its infancy. To this extent, we have begun studying, in situ, the self-assembly (SA) of long-chain alkanoic acids, from organic and aqueous media, onto the as-obtained surface of an aluminum alloy (Al6111) using electrochemical methods. Specifically, we are interested in how the physicochemical properties and morphology of a commercially relevant metal oxide surface are affected by, and affect, self-assembly. In this work, we observe that the presence of a SAM of stearic acid induces substantial changes in the passivation of the Al6111 alloy. We propose a simple model to quantitatively describe these changes and provide a physical description of the SAM's role.