Molybdenum-based electrocatalysts are promising candidates of platinum (Pt)-based materials in electro- catalyzing hydrogen evolution reaction (HER), due to their cost-efficient and resembled electronic prop- erties. Reported herein is the preparation of molybdenum carbide nanoparticles uniformly decorated on nitrogen-modified carbons (Mo 2 C/NC) through the carbonization of Mo-based polymers under hydrogen atmosphere by using poly( p -phenylenediamine) and ammonium heptamolybdate polymer analogue as precursors. And the molybdenum nitride nanoparticles loaded on porous N-doped carbons (Mo 2 N/NC) are also fabricated by calcination the polymer precursors in nitrogen gas. The Mo 2 C/NC shows more ex- cellent electrocatalytic activity than Mo 2 N/NC in 0.5 M H 2 SO 4 , together with robust long-term durabil- ity. The well-crystalline nanoparticles and the increased electron conductivity are the main characters responded for the high catalytic efficiency of the fabricated electrocatalysts. This easily fabrication pro- cedure may provide a facile route to prepare non-noble metal carbide/nitride catalysts featuring well- engineered structural and textural peculiarities for realistic energy conversion system.