Since 2002, the chemical package XOXTM has been an integral part of two specific industrial insulations to actively and continuously inhibit corrosion under insulation (CUI). The package relies on liquid water infiltration as a catalyst to provide a layer of corrosion protection for the life of the insulation. This paper explains, at a molecular level, how this time-tested package, which is integral to domestic calcium silicate and expanded perlite insulations, engages a two-pronged defense (physical coating and pH buffering) against CUI. Included are recent, third-party test results that compare the corrosion performance of several common industrial insulations using mass loss corrosion rates (MLCR) when tested in accordance with the latest ASTM consensus method adopted in 2005.