Many economic and environmental restrictions have resulted in the increase of use of dry cooling technology. An effort to minimize the consumption of water is one of main reasons why researchers and engineers are working on technologies for dry cooling which does not use water. Production of electricity in power plants is an important industrial activity where the wet cooling process is commonly utilized by means of cooling towers with a huge consumption of water which is evaporated into the atmosphere. An alternative technology for the withdrawal of the waste heat is the use of air-cooled condensers. Such condensers use the fan-forced air for water steam condensation and waste heat removal to the ambient environment. Apparently, the overall efficiency of the power plant is influenced by the design and performance characteristics of the air-cooled condenser. A proper setup and layout of the air-cooled condenser is therefore an important issue in the design and/or in the retrofits of power plants utilizing dry cooling systems and air-cooled condensers. A CFD analysis is a computational approach that is commonly utilized for the thermal analysis of the air-cooled condensers. However, CFD models and simulations are computationally demanding and often tricky. In the paper, the semi-empirical computational tool applicable for design and thermal investigations of air-cooled condensers is presented. The model is fast enough to complete simulations of operation of air-cooled condensers within dozens of minutes. The tool represents a unique combination of a simple numerical control-volume-based model of the air-cooled condenser which is coupled with empirical relationships gained from the literature. A good agreement between the semi-empirical model, data sheet parameters provided by producers of air-cooled condensers and experimentally gained data was achieved.