Desiccant wheel is an important and crucial component that can be used in building HVAC systems in order to reach relevant energy savings and to use renewable sources. The optimization of air handling units based on desiccant wheels instead of conventional components is complex and it requires adequate simulation tools. In the present paper desiccant wheels performance and optimization are investigated. The analysis is carried out through a one-dimensional gas side resistance model which considers developing temperature and velocity profiles along the channels. Simulation results show a good agreement with experimental data available in literature in a wide range of operating conditions. The model is used to analyze the influence of working conditions on desiccant wheel performance and on the optimal revolution speed. Several performance criteria are introduced and each one of them is used to investigate and to find out the optimal desiccant wheel configuration. For each criterion the best process air angular sector and revolution speed are identified, and the obtained results are compared. Through a practical example it is finally shown how each criterion leads to different optimal configurations. (C) 2010 Elsevier B.V. All rights reserved.