Room‐temperature anodic oxidation (ANO) followed by rapid thermal nitridation in N2O was used as new method to prepare thin nitrided oxides. It was found that the ANO nitrided oxides demonstrate better interfacial property and breakdown endurance than rapid thermal oxidation (RTO) nitrided oxides. The concentration of nitrogen incorporated in ANO nitrided oxide is larger than that in RTO nitrided oxides. It is believed that the loose density and the existence of hydrogen related species in anodic oxides formed by room‐temperature anodization cause nitrogen to diffuse easier into oxide and pile up at Si/SiO2interface during N2O nitridation. In addition, the self‐readjustment of anodization current through the weak path in oxide is beneficial to thin gate oxides. ©1996 American Institute of Physics.