Diacerein is a drug for osteoarthritis and is di-acetylated derivative of rein. Aceclofenac is used as an effective non-steroidal anti-inflammatory drug (NSAID) with anti-inflammatory, analgesic, and antipyretic properties. The present study describes degradation of diacerein and aceclofenac under ICH prescribed stress conditions (hydrolysis, oxidation, dry heat, wet heat, and photolysis) and establishment of a stability-indicating HPTLC assay method. Different degradation peaks were observed for diacerein when it was exposed to alkaline, and acid catalysed hydrolysis. For aceclofenac, decrease in peak area was observed with single peak of degradation product after oxidation. For HPTLC, RP-18 F254s pre-coated plates, and mobile phase consisting of methanol: water 7: 3 v/v was used to achieve separation. Quantitation was done at 268 nm. The method was validated as per ICH Q2 R1 guidelines and results were in limit. The method was found to be simple, specific, precise, and stability indicating.