This study was carried out on the cotton varieties; Giza 45, Giza 77, and Giza 85, to investigate the effect of the chemical treatments; scouring, mercerization and resin treatment on fiber properties. The In­frared reflectance spectroscopy was used to analyze the treated fiber and study the Infrared bonds characteristics of the hydrogen bonded structure of cellulose to qualitatively evaluate the changes in the struc­ture, that are reflected in differences in the physical properties of the treated fibers. It was found that the response to different treatments depends on the formation of hydrogen bonds produced, the resin treatment have the medium response between the scouring and mercerizing for all the measured properties.