The book chapter on the chemical stability of drugs provides a comprehensive overview aimed at pharmaceutical scientists, researchers, and professionals engaged in drug development, manufacturing, and quality control. The chapter objectives include understanding the significance of chemical stability for ensuring pharmaceutical safety and efficacy, identifying factors influencing chemical stability, exploring degradation pathways, grasping kinetics for predicting shelf-life, and mastering stability testing methods. The chapter serves as a foundational resource for professionals in the pharmaceutical industry, equipping them with essential knowledge and tools to ensure the quality and safety of pharmaceutical products throughout their lifecycle. It emphasizes the interdisciplinary nature of chemical stability, bridging pharmaceuticals, food chemistry, and materials science.