The aim of work is to isolate Lansoprazole intermediate impurity resulting into its yield improvement. Lansoprazole is a proton pump inhibitor, generally used in treatment of peptic ulcer. Lansoprazole is synthesized in seven stages. Meta-nitro impurity i.e. (2, 3-dimethyl-5-nitropyridine-N-Oxide) occurs at stage II which is isolated by a very conventional method and elemental analysis is performed by Proton NMR and IR.