The laminar fully developed free-convection flow in a channel bounded by two vertical plates, partially filled with porous matrix and partially with a clear fluid, has been discussed when both the plates are moving in opposite direction. Two regions are coupled, by equating the velocity and shear stress at the interface. The momentum transfer in porous medium has been described by the Brinkman-extended Darcy model. The affect of Darcy number on flow velocity has been discussed in fluid region, interface region and porous medium with the help of graphs. Analytic method has been adopted to obtain the expressions of velocity and temperature. The skin-friction component has also been determined and presented with the help of tables.