Abstract: The flux of carbonyl sulfide between the atmosphere and the underlying forest has been measured by a flux-gradient technique on the 50m tower of the forestry faculty of the University of Goettingen in the Natural Reserve Solling in Central Germany. The site is covered by beech and spruce of 120 and 80 years of age, respectively. The canopy height is around 28 meters. Carbonyl sulfide was sampled simultaneously at 32. 38 and 50m above the ground by cryo-trapping over lOmin intervals. Samples were analyzed by GC/FPD. Fluxes of COS above the forest were derived from COS gradients and diffusivities of heat and water vapor. Diffusivities were derived from gradients and fluxes of heat and water vapor measured simultaneously with COS. Twenty sets of profiles have been obtained during daytime under stable boundary layer conditions. Each of the individual profiles showes a decrease of COS towards the top of the canopy that exceeds the analytical uncertainty of the measurement, indicating uptake of COS by the forest. An average COS flux of -(143±54) ng COSm-2·s-1 have been obtained.