Textiles treated with nanoencapsulated phase change materials (nanoPCMs) were used to examine their suitability as clothing materials to prepare thermostatic clothes for absorbing or releasing heat according to heat fluctuation between the body and the environment. To this end, the physical and mechanical properties of fabrics treated with nanoPCMs, such as nano-nonadecane and nano-octadecane, were evaluated after we confirmed the morphology and thermal efficiency of the nanoPCMs. The nanoPCMs were almost spherical, with an irregular size distribution between 200 and 400 nm. The heat of fusion and peak temperature of melting for nano-nonadecane, nano-octadecane, and a balanced mix were measured at 102.6 J/g and 33.6 degrees C, 144.7 J/g and 29.8 degrees C, and 137.4 J/g and 31.8 degrees C, respectively. However, the heat of fusion of the vapor-permeable and water-repellant (VPWR) fabrics treated with the nanoPCMs were only 6.8, 4.0, and 3.6 J/g, respectively, because the weight of fabric was added per unit area. The air permeability of the specimens without nanoPCMs was the lowest; that of the VPWR fabrics with nanoPCMs was relatively higher. The water vapor transmission of the VPWR fabrics with nanoPCMs was higher than the fabric without nanoPCMs, and the water resistance decreased in the same order. Compared to the mechanical properties of the fabric without nanoPCMs, the stiffness and roughness of the fabrics with nanoPCMs were improved, but the resilience and smoothness of the fabrics were slightly decreased. Consequently, the physical and mechanical properties of VPWR fabrics with nanoPCMs were superior to those of the fabric without nanoPCMs. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 3238-3245, 2011