Rabeprazole sodium (Aciphex) is a gastric proton pump inhibitor used for the prevention and treatment of gastric acid related diseases. During the synthesis of bulk drug of rabeprazole sodium we observed seven impurities, in which four are new impurities. All the impurities were detected by a gradient high performance liquid chromatographic (HPLC) method, whose area percentages were ranged from 0.05 to 1.0%. LCMS was performed to identify the mass number of these impurities. A thorough study was carried out to characterize the impurities. These impurities were synthesized, characterized and were co-injected with the sample containing impurities and are found to be matching with the impurities present in the sample. Based on the complete spectral analysis (IR, NMR and Mass) these impurities were characterized as Rabeprazole sulphone [Impurity:1]; Rabeprazole sulphide [Impurity:3]; 1H- benzimidazole-2-thiol [Impurity:5]; 2-[[chloro[4-(3-methoxypropoxy)-3-methylpyridin-2- yl]methyl]sulfinyl]-1H-benzimidazole [Impurity:6]; 2-[[chloro[4-(3-methoxypropoxy)-3-methylpyridin-2- yl]methyl]sulfonyl]-1H-benzimidazole [Impurity:7]; 5-[1H-benzo[d]imidazol-2-ylthio]-2-[[4-(3-methoxypropoxy)- 3-methylpyridin-2-yl]methylthio]-1H-benzo[d]imidazole [Impurity:8]; 1-[[1H-benzo[d]imidazol-2-ylthio][4-(3- methoxypropoxy)-3-methylpyridin-2-yl]methyl-2-[[4-(3-methoxypropoxy)-3-methylpyridin-2-yl]methylthio]-1Hbenzo[ d]imidazole [Impurity:11]. Of which impurities 6, 7, 8 and 11 are new impurities.