Wagner’s theory of oxidation and the Deal-Grove model are classic standards for understanding the behavior of passivating oxide films. Both predict a parabolic growth kinetics as the limiting response of these oxides. However, oxidation of certain materials (e.g., Zr, Ta, Ti, Nb and their alloys) shows a unique deviation from this classical behavior, where the rate of weight-gain undergoes a periodic acceleration while the oxide layer remains adhered to the substrate. The structure of the oxide film shows a correlated periodicity in the form of a sublayers separated by voids. A candidate approach to understand this anomaly is Turing’s theory of pattern formation. Although this theory relies on the presence of a diffusional instability in a reaction-diffusion system, it has not been applied to the classic example system of oxidation yet. Therefore, in this work, we first develop a general analysis framework to study the behavior of Turing’s diffusional instability in a moving boundary system (e.g., a growing oxide film on a substrate). Interestingly, the results show behavioral regimes strikingly similar to the periodic oxidation behavior observed experimentally. Subsequently, we propose an interaction between the crystal defects and an autocatalytic phase transformation that can cause such diffusional instability to develop within the oxide.