Abstract: Provided herein is a specific crystalline form of the anti-cancer drug birinapant, designated Form H. Compositions comprising Form H are disclosed, as well as methods of use thereof. Methods of preparation of the specific crystalline form are also provided. Form H is suitable for manufacturing drug product under GMP guidelines. Birinapant is a peptidomimetic of second mitochondrial-derived activator of caspases (SMAC), and inhibits proteins of the IAP (Inhibitor of Apoptosis Protein) family.