The subject of the paper is aimed for methodology for the evaluation of cooling tower drift eliminator performance. Two independent methods for the evaluation of eliminator performance were used. The former method is based on the numerical determination of particle trajectories in the area of drift eliminators. The latter approach applied the method commercially known as IPI (Interferometric Particle Imaging). This method seems to be the most suitable for such purposes. It is a non-invasive method based on optical interference beam passed through the transparent particles and the beam reflected by such particles. The performance of drift eliminators was evaluated by comparison of the droplet size distribution below and over them.