A systematic approach is proposed to find the optimal draw solute and the optimal system for forward osmosis (FO) desalination. Selection of a draw solute and its concentration mainly decides the water flux through FO membrane, as well as the energy requirement for draw solute recovery, i.e. the economy of FO desalination. The proposed approach selects 7 candidate compounds by screening 4058 compounds in OLI and ASPEN chemical databases. Subsequently, the membrane and distillation column processes are designed and optimized for each draw solute by establishing a cost minimization model. Finally, economies of the optimal systems for candidates are compared to find the most competitive draw solute. The proposed method will contribute to designing commercially viable FO desalination systems. (C) 2011 Elsevier B.V. All rights reserved.