We report the synthesis and magnetocaloric properties of ternary intermetallic compound ZnMnSb, which crystallizes in tetragonal crystal structure with the space group of P4/nmm. It undergoes a second order phase transition from ferromagnetic to paramagnetic at Curie temperature (Tc) of 302 and 293 K for arc melted and rapid thermal quenched ZnMnSb samples respectively under an applied field of 500 Oe. The maximum change in isothermal magnetic entropy (−ΔSM) with typical values of 1.3 and 0.8 J/kg K are found at Tc for arc melted and rapid thermal quenched samples respectively under an applied field of 20 kOe. The relative cooling power (RCP) calculated from the (−ΔSM) vs. T distribution plots are in the range of 43–48 J/kg. The critical behavior of ZnMnSb has been explained using the Arrott plots, field dependence of magnetization at Tc and temperature dependence of magnetization. The obtained values of the critical exponents δ and β are 3.385 and 0.154 for arc melted; and 2.850 and 0.102 for rapid thermal quenched samples respectively indicating that there exists a long range magnetic interaction below Tc. The moderate −ΔSM at low applied field along with broad operating temperature range, the Tc close to room temperature and the low cost of ZnMnSb make it a promising candidate for room temperature magnetic cooling applications. © 2019 Elsevier B.V.