Reverse phase high performance liquid chromatography method, for estimation of related substances or chromatographic impurities of Barcitinib was developed and validated. Baricitinib was developed by separating its degradation products on a X-Terra RP18 (150x4.6mm, 5.0 µm) column using 0.1% Tri ethyl amine in water adjusted pH-2.5 with OPA and Acetonitrile in simple gradient at a flow rate 1.0 ml/min. The column effluents were monitored by a photodiode array detector set at 224nm. The method was validated in terms of specificity, linearity, accuracy, precision, detection limit, quantification limit and robustness. Forced degradation of Baricitinib was carried out under acidic, basic, peroxide, reduction, thermal, photo and hydrolysis conditions. The proposed method is validated as per ICH Q2 (R1) guidelines. The proposed method is simple as selected chromatographic conditions are not so difficult to apply in routine analysis for testing the chromatographic impurity of baricitinib.