Liquid desiccant dehumidification is an effective method for extracting moisture from humid air and consumes less energy than conventional methods. Exergy is an essential tool to analyze liquid desiccant dehumidification systems. The problem with current exergy analysis of liquid desiccant dehumidification systems is that the exergy calculation for humid air is inconsistent with the exergy calculation for liquid desiccant. The choice of the dead state is the key issue in exergy analysis. In this paper, the saturated air state of ambient temperature is selected as the ultimate dead state. The ultimate dead state of liquid desiccant is defined by limitation of the infinitely diluted solution that will guarantee the uniqueness of the ultimate dead state in the system and address the previously mentioned inconsistency. The exergy flow in the liquid desiccant dehumidification cycle is also calculated (LiBr aqueous solution is used as an example), and exergy expressed per kilogram of dry air and per kilogram of solute can simplify the calculations. Exergy destruction, a measurement of irreversibility in the heat and mass transfer process, indicates the direction of system improvement. (C) 2013 Elsevier B.V. All rights reserved.