In this work, highly porous MoS2 nanostructures have been synthesized via a one-pot and versatile calcination of cyanamide and (NH4)(2)MoS4 precursors. At first, the thermal polymerization of cyanamide into carbon nitride suppresses the aggregation of MoS2. Then, the thermal decomposition of the formed carbon nitride brings about plentiful pores with a size of 4-70 nm in MoS2 nanostructures, generating an extremely large specific surface area up to 311 m(2) g(-1). Due to the high specific surface area and abundant exposed edge sites, the resultant porous MoS2 (p-MoS2) nanostructures exhibited outstanding electrochemical hydrogen evolution (HER) activity in a 0.5 M H2SO4 aqueous solution. The onset over potential and the overpotential at a current density of 10 mA/cm(2) were as low as similar to 30 mV and similar to 130 mV, respectively, which is superior to the previously-reported MoS2-based HER electrocatalysts. (C) 2016 Published by Elsevier B.V.