Efavirenz (EFV), an antiretroviral drug, was evaluated for its degradation behaviour in solution state. A total of twelve degradation products were detected on high performance liquid chromatography (HPLC) analyses. Initially, comprehensive mass fragmentation pattern of the drug was established by direct injection and collection of high resolution mass spectrometry (HRMS) and multi-stage tandem mass spectrometry (MSn) data. Subsequently, LC-HRMS studies were carried on the stability samples containing the degradation products. Eleven degradation products were isolated and subjected to 1D and 2D nuclear magnetic resonance (NMR) studies for their structural confirmation. The collated information was utilized for the characterization of all the degradation products and hence in outlining the comprehensive degradation pathway of the drug. In-silico toxicity of the degradation products was evaluated by TOPKAT analyses.