The process of combined natural convection heat and mass transport during dissolution of a vertical soluble metallic substrate in an otherwise quiescent molten metallic pool is studied theoretically. The problem is formulated using the Boussinesq approximation, taking full account of the density variation of the binary metallic solution due to concentration and temperature differences across the dissolution boundary layer. Also accounted for are the solubility of the metallic substrate on the species transport and the motion of the solid-liquid interface at the dissolution front. The governing system is solved using a combined analytical-numerical technique to determine the velocity, temperature, and concentration profiles in the dissolution boundary layer. Results are presented showing the dependence of the rate of dissolution on the key controlling parameters of the binary metallic system.