Jute fiber was treated with three different hydroxy benzene diazonium salts in acidic and basic media. The formation of coupling with lignin in the polymer system was observed by the infrared spectra and nitrogen content estimation. The physico-mechanical properties, viz., tensile strength, tenacity, elongation at break, moisture regain, shrinkage, and loss in weight of jute fiber were studied. The tensile strength, tenacity, and moisture regain properties of the treated fiber were found lower in comparison to those of raw (control) fiber. However, higher tensile strength and tenacity of the fiber treated with ortho hydroxy benzene diazonium salts in comparison to fiber treated with meta hydroxy benzene diazonium salts were observed. The tensile strength and tenacity of the fiber treated with meta hydroxy benzene diazonium salts were higher than those of the fiber treated with para hydroxy benzene diazonium salts. The elongation at break of the treated fiber is found greater than that of the raw fiber. The fiber treated in basic media shows higher tensile strength than that treated in acidic media. The formation of metallated azo complex compound on jute fiber was observed by infrared spectra. The nature of the shades developed on jute fiber was also reported. Copyright © Taylor & Francis Group, LLC.