The hot alkaline solution not only reduces the weight of polyester. but also can be used for mercerization of cotton. The alkaline solution also cxhibits desizing and scouring action on cotton fabrics at high temperatures. In this study the effects of alkali concentration and reaction time on the weight loss of the polyester component. Mercerization of the cotton component and other properties of the polyester/cotton fabrics were investigated when they were treated at high temperatures. Furthermore the possibility of omitting the resizing and scouring processes was studied.