The paper critically examines, within the framework of linear analysis, thermosolutal instability of an incompressible, viscous fluid confined in a porous medium in the presence of magnetic field, analytically and numerically both. The analytical discussion provides the sufficient conditions of stability and instability and the characterization of modes. By actually calculating the root of eigenvalue equation (of degree 4) neutral stability curves are drawn. The numerical results show the effect of various physical parameters on the critical wave number ac. It is concluded that RD-1 , S and R4 have stabilizing character and Richardson number J has destabilizing character. The non-dimensional parameter R2 shows a dual character, which depends upon thermal diffusivity ?