Infrared spectra of treated cotton linters and bleached cotton stalk pulp with different concentrations of ethylene diamine and zinc chloride solution are studied. The structural changes brought about by these treatments have been studied from infrared spectral diagrams. It is found that the crystallinity index calculated from the infrared spectral data of these treated pulps decreases with increasing concentration of ethylene diamine and zinc chloride. The decrease in the crystallinity index (Crl) of the treated pulp with zinc chloride is higher than in case of treatment with ethylene diamine (EDA). The detectable frequency change at the hydrogen bonded OH of cotton linters by treatment with zinc chloride and ethylene diamine reflects the contributions of this bond in the swollen pulp. The dielectric study of these treated pulps confirmed the molecular structural changes determined from IR spectroscopic study.