A hot air stream was successfully cooled across the heat transfer surface of a cross-flow finned plate heat exchanger with honeycomb structure of aluminum while fine water droplets accompanied in excess over saturation were evaporated in a cold air stream. Hot stream temperature efficiency is improved over that without sprayed droplets and attained up to 60% in a typical example, even at high ratio of hot/cold air flow rate of 4 and a small fraction of water droplets, as small as 0.3% wt. The effect of flow rate ratio and amount of accompanied droplets on heat transfer performance is investigated to propose a scheme of so-called self cooling in which a cold air stream was prepared by spraying water droplets to a part of process air. Thus cooling under constant humidity reduces enthalpy in contrast to the conventional direct contact evaporative cooler at constant enthalpy. A high value of Ca is expected in an adsorptive desiccant cooling system equiped with the present sprayed heat exchanger.