In this paper heat and mass transfer processes in evaporative fluid coolers are discussed. A new mathematical model of evaporative fluid cooling with countercurrent air flow is presented. The model consists of four ordinary differential equations with their boundary conditions and some associated algebraic equations. A method of adjusting the model to geometrical arrangement which is used in bare-tube heat exchangers is proposed. The study presents a comparison of the results computed using an analytical model with the experimental results of the evaporative water cooler test. A good agreement between the calculated and experimental values is achieved. The correction function of mass transfer coefficient introduced into the analytical model improves this agreement.