A one-rotor two-stage rotary desiccant cooling system (OTSDC), in which two-stage dehumidification process is realized by one desiccant wheel, was investigated experimentally. The system was proposed to reduce the volume of two-stage rotary desiccant cooling system (TSDC) with two desiccant wheels without reduction in system performance by using the novel configuration. An experimental setup was designed and built to evaluate the system performance under various operation conditions. The effects of different wheel thicknesses at various rotation speeds under Air-conditioning and Refrigeration Institute (ARI) summer and humid conditions were investigated. It is observed that there exits an optimal rotation speed where moisture removal of the system D and thermal coefficient of performance COPth are both optimal. Moreover, the unit with wheel thickness of 100 mm performs better for its bigger moisture removal D and higher COPth. Generally speaking, the COPth of this unit is around 1.0 when the regeneration temperature is lower than 80 degrees C. Compared to TSDC, the OTSDC not only preserves the merits of low regeneration temperature and high COPth, but also has a reduced size by about half. (c) 2008 Elsevier Ltd. All rights reserved.