Air classification is a method used to classify feed material according to the shape, specific gravity and size of the particles and preferred where water interaction is avoided. Since it is widely used by many of the industries, this study contributes to the literature related with high efficiency air classification by considering the design and modelling aspects for cement industry. In this context various types of high efficiency classifiers operated at cement grinding circuits were sampled at the same cement quality then mass balancing studies were carried out. After all, the variation of rotor size and air amount parameters with the capacity of the classification process was investigated. Moreover, a mathematical model for high efficiency air classifiers was developed by applying the efficiency curve approach. In contrast to previous studies, the sharpness parameter (alpha) was found to be dependent on the capacity of the separation process and the diameter of the classification chamber which made the model structure unique. (C) 2014 Elsevier B.V. All rights reserved.