The objective of this study was to investigate the parameters that govern the drying process of willow chunks. Indicative chunk drying trials were conducted to assess the potential of natural wind drying. Supportive model simulations were conducted to gain insight into the influence of different process parameters (particle size, pile depth) on drying. Natural wind drying experiments showed that willow chunks could be dried from 50% (wet basis) to around 10% within 5 months. Internal heating in the pile did not occur and dry matter losses were reasonably low (3.5-5%). The drying time of willow chunks depended on drying air conditions, particle size and pile dimensions (depth). The particle size of chunks should be large enough to create a low airflow resistance in the pile, but small enough to avoid that internal diffusion of moisture limits the drying process. (C) 2003 Elsevier Ltd. All rights reserved.