The paper focus on first and second laws analysis for flow and heat transfer inside a vertical channel made of two uniformly porous parallel plates with suction/injection under the combined action of buoyancy force, transverse magnetic field and constant pressure gradient. Both vertical walls are kept isothermal at the same temperatures and the flow of the conducting fluid is assumed to be unsteady with variable viscosity. The nonlinear governing equations in Cartesian coordinate are obtained and solved numerically using semi-implicit finite difference techniques to develop expressions for velocity and temperature profiles. The entropy generation number, irreversibility distribution ratio and Bejan number are presented graphically and discussed quantitatively for various values of the embedded parameters.