Sodium Hydrogen 4-Chlorophthalate is primarily used in the field of analytical chemistry as a reagent for calibrating and testing instruments, particularly in high-performance liquid chromatography (HPLC). It serves as a standard compound to ensure the accuracy and precision of analytical measurements. Additionally, it is employed in research laboratories for synthesizing and studying more complex organic compounds, where its specific structure aids in understanding reaction mechanisms. In industrial settings, it may be utilized in the production of dyes, pigments, and other chemical intermediates due to its aromatic and functional properties. Its stability and solubility make it a suitable candidate for various experimental and manufacturing processes.