A stability indicating RP-HPLC (Reverse Phase high performance liquid chromatography) method was developed and validated for the determination of Darunavir Hydrate in bulk and tablet dosage form using C18 column CHEMSIL C18 (250 X 4.6 mm), ThermoP4000 with PDA detector in isocratic gradient system integrated high performance liquid chromatographic system with chromquest software. The methanol: acetonitrile: water was selected as mobile phase in ratio of 70: 15:15 and was filtered on membrane filter (0.45μ) at flow rate 0.5 mL/min. The detection was carried out at 263 nm and retention time of Darunavir hydrate was found to be 3.162 min Linearity was observed from 5-30 μg/ml. The correlation coefficient R2 was 0.997. Darunavir hydrate was subjected to stress conditions including acidic, alkaline, oxidation, photolysis and thermal degradation on, and the results showed that it was more sensitive towards basic degradation. The method was validated as per ICH guidelines.