Phosphotungstic acid is widely used as a catalyst in various organic synthesis reactions, including esterification, hydrolysis, and oxidation processes, due to its strong acidic and oxidative properties. It is also employed in the preparation of conductive polymers and as a staining agent in electron microscopy to enhance the contrast of biological specimens. Additionally, it finds application in the analysis of alkaloids and other nitrogen-containing compounds, where it forms precipitates for identification and quantification. In materials science, it is utilized to modify surfaces and create functional coatings with specific properties.