Electrochemical double layer capacitors (EDLCs) are promising high power energy sources for many different applications where high power density, high cycle efficiency and long cycle life are needed. However, because the energy density of EDLCs is small compared to that of rechargeable batteries one needs to increase the capacitance of EDLCs. The nanofiber diameters range from 50 nm to 400 nm, depending on the concentration of polymer solution types, tip-to-collector distance, applied voltage, and viscosity of the solution. The main advantage of the electrospinning process is that it is a simple means to prepare continuous fibers with unusually large surface to volume ratios and pore structure surfaces. So, feature of nanofiber webs are the high specific surface area developed by creating pores on the nanofiber surface. In this work, the multiwalled carbon nanotubes embedded polyacrylonitrile solutions in N,N-dimethylformamide (DMF) were electrospun to be webs consisting of 350 nm ultrafine nanofibers, which were used to produce a series of activated carbon nanofibers with developed mesoporosity and high electrical conductivity through stabilization, carbonization-activation processes.