In recent articles evaporative cooling has proved to be the utmost air-side heat transfer augmentation. This kind of augmentation, when applied to steam condensers in power plants or to refrigerants in air conditioner systems, results in a lowering of the condensing temperature, even below ambient levels. This yields a remarkable increase of thermodynamic efficiencies of both processes and, therefore, a reduction of energy consumption. The combined heat and mass transfer processes in an evaporatively cooled device are very complex, due to the vast numbers of parameters which must be considered. Previous studies have assumed it impossible to perform any analysis unless many simplifying assumptions are made. The present article indicates that analysis can be performed where none of the assumptions originally used by Merkel are made. It is demonstrated by experiments that plate-fin tube and bare tube condenser performances can be predicted reliably. The insensitivity of the analysis to geometric design eliminates the need for extensive model tests and for production of correction and design factors for the design of evaporative condensers.