In tropical, hot and humid climates where temperature and humidity level are high, air conditioning (AC) systems are necessary for providing thermal comfort to building occupants. For an air conditioned space that needs outside air ventilation to maintain indoor air quality, the ventilation air can bring sensible heat ratio (SHR) of cooling load well below 0.7 since it accounts for as high as 80% of total latent load in the space. The cooling load SHR below this value cannot be handled effectively by conventional AC systems. Handling sensible and latent load separately using a hybrid scheme is an interesting option. A desiccant system can handle the latent load while a conventional system can handle mainly the sensible load. This could help reduce overall energy consumption and provide effective control of indoor air condition. This book presents a theoretical and experimental investigation of the use of a liquid desiccant (LiCl) AC system in tropical Thailand. The system treated ventilation air before supplying it into a conditioned space. Solar energy was used for the regeneration process. A simulation procedure developed for evaluating the system performance is also presented.