The need to save energy in power producing and power consuming systems and the fact that evaporative cooling is the most efficient method for heat rejection led to the design and testing of a model of a special cooling tower, fn this hybrid system an evaporative condenser is being built into the cooling tower and the advantages of evaporative cooling are combined with those of a wet cooling tower, causing a lower condensing temperature or saving heat transfer area or both. The present work not only deals with the development of a practical model of a cooling tower module but also further develops, modifies and consolidates a computer program originally designed for horizontal finned or bare tube condensers. These modifications are associated with the vertical tube condenser in the hybrid tower considered in this work. It is shown that the performance of the model tower can be predicted by use of this computer program, as previously shown by Leidenfrost and Korenic for a different geometry. It is further shown that either the performance of a scaled-up hybrid tower can be predicted or a tower geometry can be sized for given heat rejection needs, based on inlet air state, water flow rate, and system geometry.