4-Amino-1-naphthol Hydrochloride is primarily used in the synthesis of dyes and pigments, particularly in the production of azo dyes, which are widely employed in the textile industry for coloring fabrics. Its ability to act as an intermediate in organic synthesis makes it valuable for creating complex dye molecules with specific color properties. Additionally, it is utilized in the preparation of photographic developers, where it aids in the reduction of silver halides to metallic silver, enhancing image formation. In biochemical research, this compound serves as a reagent for detecting and quantifying certain enzymes and proteins due to its reactive amino and hydroxyl groups. Its applications also extend to the field of analytical chemistry, where it is used as a chromogenic agent in various assays to visualize and measure chemical reactions.