In this paper, the waste heat from a gas turbine-modular helium reactor (GT-MHR) is utilized to produce power through two Organic Rankine Cycles (ORCs) and pure water by means of distillation processes. An Absorption heat transformer (ANT) is employed to upgrade the lower temperature waste heat in order to run the desalination system. Detailed thermodynamic analyses for the proposed combined cogeneration cycle (CC cycle) are presented and the effects of important parameters on the cycle performance were studied. The proposed cycle performance is then optimized based on the first law of thermodynamics. The results show that the first law efficiency of the CC cycle, at the optimum conditions, is around 7% higher than that of the GT-MHR cycle. It was also concluded that for each 50 degrees C increase in the gas turbine inlet temperature, the thermal efficiency is increased by around 2.5-4% and the pure water production rate is decreased by around 6.5%. The results also showed that employing R1234yf as working fluid in the ORCs instead of R123 gives almost the same results in the cycle performance. (C) 2011 Elsevier B.V. All rights reserved.