Dapagliflozin (DAP) is therapeutic agent for diabetes mellitus type II patients with insufficient glycemic control by exercise and diet. Stability-indicating LC–MS method was developed and validated on C8 column and method was able to separate DAP and three major hydrolytic degradation products. Structure elucidation of three major identified hydrolytic degradation products (DPs) and establishment of degradation pathway were executed with the combine application of liquid chromatography-positive mode electrospray ionization tandem mass spectrometry and high-resolution mass spectrometry. Further ProTox-II was used to predict in silico toxicity for each DPs and compared with DAP. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.