To improve the description of wet deposition in atmospheric dispersion models, FOI has on behalf of the Swedish Radiation Safety Authority made a literature study. Wet deposition occurs when rain and snow transport an airborne gas or particles to the ground where they deposit. Calculations after the nuclear power plant accident in Fukushima 2011 have emphasized the importance of wet deposition along the path from Japan to describe the air concentrations that reached Sweden. The purpose of this study has been to create an understanding of how wet deposition may be modeled under different circumstances, based on studies of incidents with radioactive releases, experiments and theoretical and physical modeling of wet deposition. The result from the study will during 2014 be implemented in dispersion models at FOI and be validated with measurements. For future implementations the study recommendations based on the study are the following: ? to include wet deposition from convective (small scale) precipitation. ? to include in cloud scavenging (and not only below cloud scavenging which is the case in the current implementation). ? include local calibration of precipitation data to data from the weather prediction model. The current implementation calibrates total precipitation at ground level in the whole domain. ? to use precipitation at different heights directly from the numerical weather prediction model