The conductance versus frequency technique [G(&ohgr;)] and deep level transient spectroscopy (DLTS) are both used to characterize Si‐SiO2interface states. However, no direct comparison between the two methods has yet been performed. We have performed a systematic study, with these two techniques of the same metal oxide semiconductor structures (Si‐SiO2onn‐ andp‐type materials) made with various technologies and we have compared the performances of each technique: energy range accessible, energy resolution, sensitivity. We have shown that the conductance technique provides a density of states larger than the one obtained by DLTS, that its sensitivity and energy range are smaller. Its energy resolution is also smaller as illustrated by the fact that localized levels are detected by DLTS which are not with the conductance technique.