Heusler alloys have gained important place in condensed matter physics due to their versatile functional properties such as large magnetoresistance, giant magnetocaloric effect, spontaneous exchange bias, spintronics etc. In particular, giant magnetocaloric effect was reported in systems with magneto-structural coupling, resulting from the first order magnetic phase transition. So as to strengthen the understanding of functional properties, it is mandatory to understand the magnetic structure of the compounds. Neutron diffraction characterization is an indispensable tool to understand the magnetic structure of the compounds by disclosing the individual magnetic contribution of the elements and to determine the type of universality class by extracting critical exponent. Presently, we propose to measure temperature-dependent neutron diffraction of one such compound Ni42Co8Mn38Sb12.