A novel chromatographic stationary phase for reversed-phase high performance liquid chromatography (HPLC) is provided. By using mono and dimethyl silanes as endcapping reagents as compared with the use of traditional trimethyl silanes, an improved blocking of unreacted surface silanols is achieved. The improved blocking of surface silanols results in at least better peak shape and more reproducible retention times in reversed-phase HPLC analyses.