Holmium nitride (HoN) nanocrystallites were synthesized by a plasma arc discharge technique and characterized to study their magnetocaloric properties. HoN was formed under the influence of nitrogen-argon mixed gas. N-2 gas was used as an active element for arc discharge between two electrodes maintained at a constant current. In addition, N-2 gas played an important role not only as a reducing agent but also as an inevitable source of excited nitrogen molecules and nitrogen ions for the formation of HoN phase. The ratio of partial pressure between Ar and N-2 was systematically varied to obtain single phase HoN with minimal impurities. Magnetocaloric properties were measured by applying fields up to 50 kOe in the temperature range from 6 K to 60K. The as-synthesized HoN nanoparticles have shown a change in magnetic entropy of 27.5 J/kgK with a transition temperature at 14.2 K thereby demonstrating their ability to be applied as an effective low temperature magnetic refrigerant material towards the re-liquefaction of H-2. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.