Accidental dangerous releases either toxic or flammable can occur during process, storage or transportation. Though the dispersion and modelling of large releases of dangerous products have already been studied, small releases (small plumes dispersion) are seldom concerned even if they are more likely to occur. Modelling of cloud dispersion downwind a water spray and the effectiveness of such a protection device for small releases are even less studied, even if water sprays are proved to be good protection devices against toxic or flammable clouds. Therefore, this paper focuses on dispersion of small plumes of chlorine both in open field and in presence of a water spray and on its modelling, The description of the dispersion model elaborated during this study, namely RED, is followed by the comparison between the predicted concentrations and the observed concentrations collected during field experiments. Conclusions are presented. (c) 2005 Elsevier Ltd. All rights reserved.