The main purpose of this work is to examine whether or not, and to what extent, the environmental impacts of Reverse Osmosis (RO) desalination varies due to different Life Cycle Impact Assessment (LCIA) methods. An RO desalination plant in the United States was chosen in the Life Cycle Assessment (LCA) using a generic LCIA method, CML2, and an US-specific method, TRACI, to assess the environmental cost in different impact categories. The input and output flows of the RO plants were based on the previous study. Life cycle inventory (LCI) used was adopted from the Ecoinvent Database with specific US datasets. The results indicated the choice of LCIA method did make a significant difference in the LCA characterization results of the desalination process. The divergence in the coverage level of different material flows, characterization models engaged in the method, and differentiation of environmental interventions between two LCIA methods were identified as the major reasons for the disparate characterization scores in various impact categories including acidification, eutrophication, photochemical oxidation, human health, and ecotoxicity potentials. This work also provided some suggestions in choosing the appropriate LCIA method for desalination industry and developing desalination-specialized LCIA method. (C) 2011 Elsevier B.V. All rights reserved.