Cinnoline hydrochloride is primarily utilized in organic synthesis and pharmaceutical research. It serves as a key intermediate in the development of various heterocyclic compounds, which are often explored for their potential biological activities. Researchers use it to study and synthesize molecules with potential therapeutic properties, such as antimicrobial, anti-inflammatory, or anticancer agents. Additionally, it is employed in the preparation of dyes and pigments due to its aromatic structure, which can contribute to color stability and intensity. Its role in chemical research also extends to the study of reaction mechanisms and the development of novel synthetic pathways.