This article describes the standardization of the surface quantification with Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) on International Standard Organization (ISO). The relative sensitivity factor (RSF) method is widely used for the quantitative surface analysis by AES and by XPS, and proposed as ISO/DIS 18118 : Surface chemical analysis —AES & XPS— Guide to the use of experimentally determined relative sensitivity factors for the quantitative analysis of homogeneous materials. Three types of the RSFs have been used in this standard: elemental relative sensitivity factors (ERSFs), atomic relative sensitivity factors (ARSFs), and average matrix relative sensitivity factors (AMRSFs). The ERSFs are the simplest and easiest to apply. However, they are least accurate be-cause no account is taken of matrix correction factor. The ARSFs are more accurate than the ERSFs because they take account of atomic density correction. The AMRSFs are most reliable RSFs in that there is almost complete correction of matrix effects. Then, it is recommended that the AMRSFs be used for the practical quantitative surface analysis of wide variety of solid materials by AES and XPS.