The purpose of this study is to investigate the performance of a thermally regenerated desiccant system at two extreme ambient conditions (high sensible and high latent load) and to report the results using quantitative measures, such as latent capacity and latent coefficient of performance (COP), that better describe the efficiency of the moisture removal process. For this study, latent COP is defined as the latent capacity divided by the total energy input of the process. In addition to testing at two different inlet air conditions, several operating parameters, such as desiccant wheel speed, regeneration temperature, and face velocity, were varied to quantify their impact on system performance. The results will be used to improve the understanding of the operation of desiccant systems and to optimize their performance by changing certain operating parameters or improving components.