Open ended nitrogen-doped carbon nanotubes (N-doped CNTs) are synthesized by pyrolysis of acetylene/ammonia (C2H2/NH3) mixture over lanthanum nickel (LaNi5) alloy catalyst and subsequent 3M, HNO3:H2SO4 acid mixture treatment. Transmission electron microscopy and X-ray photoelectron spectroscopy evaluations of the acid treated N-doped CNTs reveal that the nanotubes possess an open ended morphology and oxidation of pyridinic N groups, respectively. The resultant open ended N-doped CNTs tested as a supercapacitor electrode material by cyclic voltammetry and exhibits high specific capacitance of 146 F g(-1). (C) 2014 Elsevier B.V. All rights reserved.