The effect of three different nonionic surfactants on the mild steel in artificial corrosive oil were studied. Potentiodynamic polarization measurements were depicted that the investigated inhibitors acts as mixed type inhibitors. The SEM was used to justify the practical results. The relationship between molecular structure and the inhibition efficiency were evaluated using PM3 semi-empirical method. The inhibition efficiency was matched with the most calculated quantum chemical parameters namely EHOMO (highest occupied molecular orbital), ELUMO (lowest unoccupied molecular orbital), the energy gap ∆E, the Mulliken charges, the hardness η, the dipole moment µ, the total energy change ET, the electron affinity A, the absolute electronegativity x, the fraction of electron transfer ∆N and the electrophilicity index ω.