The recycling of post consumer cotton textile waste is highly requested, due to the high environmental impact of cotton production. Often cotton is mixed in blends with polyethylene terephthalate (PET). For the generation of high value products from recycled cotton, it essential that PET is separated from the cotton first. In this contribution, the depolymerization of PET in cotton / PET blend is investigated for the separation of PET from cotton fibers. Ionic liquids and NaOH are used as catalysts for the depolymerization reaction in ethylene glycol (glycolysis). It will be shown that ionic liquids have no significant influence on the conversion of PET. However, 99% conversion is achieved in this process with 2 w/w % NaOH as catalyst. This enables the selective depolymerization of PET in presence of cotton and gives rise to an easy separation of cotton from cotton / PET blends.Paper for the 14th World Textile Conference, May 26th-28th2014, Bursa, Turkey.