This paper studies convective instabilities in a horizontal porous layer permeated by incompressible, thermally and electrically conducting fluid by using Brinkman model in the presence of uniform vertical magnetic field and solute for both stationary and overstability cases. The linear stability equations are solved by using expansion of Chebyshev polynomials. We conclude that the system becomes more stable when the free surface conduct and when the permeability of porous medium decreases.