The oxidation of III-V semiconductors is a crucial technological process in the mass-volume manufacturing of (singlemode) Vertical-Cavity Surface-Emitting Lasers or in the fabrication of more-recently-demonstrated integrated photonic devices. To facilitate the deployment of VCSELs in their up-rising markets but also to sustain the above-mentioned emerging uses, the shape and size of the optical/electrical apertures resulting from the selective lateral oxidation of buried layers of aluminum-containing III-V semiconductors needs to be controlled with an ever-increasing accuracy and reliability.In this paper, we will review the recent experimental investigations and model developments we have carried out to analyse and describe in detail this oxidation process. In particular, we will show that its degree of anisotropy depends on the oxidation process conditions and that the detrimental shape distortion induced by this anisotropy may be mitigated by a careful design of the etched mesas used to enable the oxidation of the buried layers.