Abstract. In the frame of Thermodynamics of irreversible process, a model describing the thermomagneto-mechanical behavior of a single crystal of Ni-Mn-Ga is built. The choice of internal variables is linked to the physics of the problem (fraction of martensite variants, fraction of Weiss domains, magnetization angle). The simulations permit to describe the paths in the space (stress, temperature, magnetic field) in agreement with experimental tests. A special attention will be devoted to the control laws required to use these functional materials as sensors or actuators.