This report provides a technical description of the RIVM/KNMI PUFF model. The model may be used to calculate, given wind and rain field data, the dispersion of components emitted following an accident, emergency or calamity; the model area may be freely chosen to match the area of concern. The report concentrates on model structure and on model inputs and output. The significance of input parameters is explained and first order estimate values for these are provided. The model's inputs and output are illustrated using examples.<br>