Using low-cost nonprecious metals to replace Pt as hydrogen evolution reaction (HER) electrocatalyst is promising, but still limited by their efficiency and stability. Herein, with low-cost dicyandiamide and metal salts as precursor, FeCo alloy nanoparticles encapsulated in nitrogenated carbon nanotubes (FeCo-NCNTs) were facially synthesized as efficient HER electrocatalyst. Addition of iron as second element, though not facilitating the formation of carbon nanotube, was utilized to improve the physicochemical properties of metals. Via optimizing the atomic molar ratios of Fe/Co nanoparticles, the optimal Fe0.4Co0.6-NCNTs with thin carbon shell (c.a. 5-10 layer) and equally distribution of embedded alloy nanoparticles was found with outstanding HER activity. To achieve a current density of 10 mA cm(-2), only overpotential of 50 mV, 157 mV and 202 mV were needed in acidic (0.5 M H2SO4), alkaline (1 M KOH), and neutral solutions. Its higher electrochemically active surface areas and lower electron transfer resistance may contribute to the excellent electrocatalytic HER. Furthermore, the illustrated current density slightly changed over 20 h, suggesting excellent stability. Hence, the present method provides cost-effective, high efficiency, and stable materials in developing the sustainable energy conversion systems. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.