The desiccant wheel is a key component of open desiccant air-conditioning systems. Development of a simplified method of assessing their dynamic performance would assist the growth of the industry. Important errors can occur when constant values of the effectiveness parameters are assumed in the effectiveness method. The present work investigates the feasibility of using different interpolation methods to predict the influence of the inlet states of the process and regeneration airflows on the global behaviour of a desiccant wheel. The procedures require a set of reference operating cases. One approach considers interpolation on a grid of known reference points, in a triangular arrangement, for each inlet state domain. The second approach is based on the radial basis function, where all points of the reference grid influence the estimated values. The reference cases are simulated by a validated numerical model. Comparison of the methods shows that the second approach requires fewer reference cases and so is more suitable for the development of a generic simplified tool that takes into account the influence of variable airflow rates and rotation speed on the performance. (C) 2014 Elsevier Ltd. All rights reserved.