A hybrid latent heat storage and spray flash evaporation system has been devised in an attempt to develop an energy saving desalination system that stores intermittent thermal energy such as waste heat, solar heat or heat fi om the surplus steam of a power station at night and utilizes the stored energy not only for the generation of process steam from seawater for industries and domestic air conditioning but also for the production of fresh water from the generated steam for industrial and domestic uses on demand. Experimental results of the transient discharge characteristics of the heat storage column packed with the phase change material and the transient spray flash evaporation characteristics are reported. It is also shown that by using the numerical results of the discharge characteristics and the empirical equation of the efficiency of spray flash evaporation, the amount of generated steam and produced water can be predicted with sufficient accuracy. The utilization of more than 95% of the amount of stored energy for the generation of process steam and the production of fresh water, substantiated experimentally, confirms the high efficiency of the hybrid system.