This paper presents comparison between sorption isotherms of a Jersey knitted fabric and frayed yarns which constitute. An experimental device, built around a magnetic suspension balance, was conceived to determine the sorption kinetics. This device is used to measure the moisture content of bleached textile samples made of cotton at temperatures of 25 degrees C and 35 degrees C. The results show coincidence between adsorption and desorption isotherms of knitted fabric and frayed yarns at weak humidity. The difference between sorption isotherms of the two samples, at high humidity, is explained by geometrical consideration. The knitting infects the swelling of yarns then it decreases their sorption capacity. BET and GAB models are used to fit experimental results