Porous hollow carbon nanofibers (PHCNFs) using styrene-acrylonitrile copolymer (SAN) solution as core and polyacrylic acid (PAA) as shell were manufactured by co-axial electrospinning technique, taking polyvinyl pyrrolidone (PVP) as a pore inducer additive in the shell. The shell thickness of PHCNFs could be adjusted by controlling flow rates of core and shell fluids. The prepared PHCNFs showed excellent electrochemical properties with the high specific capacitance of 221 Fg(-1) and superior cycling stability, remaining a capacitance retention of 95% after 5000 cycles under a scan rate of 0.1 Vs(-1). In this system, hollow structures bring a 20% capacitance improvement, while the porous morphology brings a 47% capacitance improvement. The attractive performances exhibited by these sponge supercapacitors make them potentially promising candidates for future energy storage systems. (c) 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43397.