o-Dianisidine is used as a redox indicator. It is used as an intermediate for the preparation of azo dyes, pigments and o-dianisidine diisocyanate, which finds application in adhesives, polyurethane elastomers and resins. It is also used in various industries like leather, paper, plastics, rubber, and textiles. It acts as a reagent to detect metals, thiocyanates, and nitrites.