In this project, the Ni-Mn-Sn and Ni-Mn-Ga alloys have been prepared by Zn and Cu doping. The obtained results on magnetic and structural properties of these alloys show that the martensitic transition (MT) increases and shifts to near room temperature due to the changes in number of conduction electrons per atom (e/a) and the unit cell volume. Then, the magnetocaloric properties of these alloys have been calculated and measured by indirect and direct methods. The obtained results by direct method show that the Zn doping of the Ni-Mn-Sn alloy led to a significant enhancement of the value of the adiabatic temperature changes (?Tad). Further study on cyclic behavior of magnetocaloric effect indicates the response of these alloys decreases under subsequent magnetic field and this is the challenging part for practical application in refrigeration. To induce a reversible transition, due to the wide temperature hysteresis, a combination of a magnetic field with a significant external mechanical effect is needed. Ab initio computations were carried out to provide the theoretical guide to gain a deeper insight into the role of Zn and Cu dopant in the MT and magnetism. By ab intitio calculation, the site occupancy variation of Zn was analyzed. The results demonstrated that in a fully ordered structure, Zn atoms prefer to occupy the sublattice of the host element in deficiency. The effective parameter on MT temperature was explained using the density of state and tetragonality results. The second part of the project was focused on the structural and magnetic properties of Ni-Mn-Ga alloys. The obtained results show that the martensite phase of these samples contains modulated structure, and therefore they have the potential for using in magnetic shape memory actuator. Our magnetic characterization indicates the kinetic arrest phenomenon in Ni-MnGa alloy, and due to this effect, the good magnetocaloric effect can not be expected.