Smart textile is considered to be a new trend that can revolutionize the functionality of clothing. One of the most promising fields of smart textiles is in energy storage devices. Recently, many research efforts focus on supercapacitor as an energy storage device that can overlap the gap between conventional batteries and traditional capacitors. Activated carbon fiber (ACF) is one of the important candidate for this application. Different groups of non-woven polyester fabrics were prepared with and without adding the activated carbons. The effect of structure of the samples on the permittivity, dielectric loss as well as the ac-conductivity is investigated and interpreted. The mechanism of the storage of the charge carriers is given by two different capacities. The first one is the capacity of the electric double layer at the interface between the electrode and the dielectric material. The second is the capacity due to the redox or what is called pseudo capacity. In this work, the broadband dielectric spectrometer, BDS, is employed to study the effect of frequency in the range of 1mHz – 10 MHz and sometimes temperature (20 – 60 oC). The non-woven samples prepared with ACF showed the best results among the prepared nonwoven samples without activated carbon fibers and even nonwoven samples with carbon granules. This is due to the good electrical conductivity of activated carbon fiber used in the nonwoven samples.