Many yarns are made from chemical fibers with various kinds of functional properties, and filament yarn surpasses spun yarn in terms of mechanical properties. However, in this century, “comfort”, “safety”, “user-friendly” and “green” are key concepts. The Food and Agriculture Organization of the United Nations (FAO) officially launched the International Year of Natural Fibers (IYNF) 2009 to celebrate the virtues of cotton, flax, sisal and hemp, and also those of wool, alpaca, camel hair and angora. In order to make effective use of natural fibers and reduce carbon dioxide emission, it is worthwhile to design and develop new spun yarns from vegetable fibers.It is also known that, in comparison with ring spun yarn, open-end spun yarn is inferior in quality. So, to produce open-end rotor spun yarn with novel functional properties, we investigated how to give it greater extension (and/or stretch), as in synthetic filament yarn. Thus, 100% cotton hollow yarns were produced using a hybrid open-end rotor spinning frame and an experimental covering machine, and the resulting mechanical properties were assessed.