In this article, we seek to locate the frontier molecular orbitals involved in the protonation reactions of substituted phenols using the FERMO concept, quantifying the orbital coefficients of the carbon and oxygen atoms involved. Once these orbitals are identified, we seek to compare the computational results with experimental NMR data obtained in the literature. In addition, we also search to computationally evaluate these stereo-electronic effects that govern reactions of aromatic electrophilic substitution using an experimental study as an example.