The utilization of low-grade heat could significantly reduce energy consumption in thermal desalination plants. This paper studies the feasibility of using low-grade heat for thermal desalination via a hybrid absorption heat pump system, in which ammonia-water is the working fluid. A thermodynamic model was proposed to simulate the operation for freshwater production of 5000 T/day using multiple effect distillation (MED) technology. Results from the evaluation showed that the performance and waste-water usage are affected by operating pressures and temperatures. Based on Net Present Value evaluation, the economic profitability could be achieved at recommended operating conditions of absorption pressure (<25 bar) and generation temperature (>30 degrees C) at a generation pressure 5 bar. A case study is presented in which water at 90 degrees C, discharged from process industry in the Sheffield region, is used for generating 20,000 T/day of freshwater. The system proposed consisted of four-stage sequential heat pumps with different operating configurations. These served as individual MED stages. The coefficients of performance were evaluated to be 3-11. According to the specific power consumption, the proposed system is a competitive technology compared with reverse-osmosis technology. Economic profitability could be achieved in 3 years. (C) 2011 Elsevier B.V. All rights reserved.