In an oligotrophic moorland pool in The Netherlands, S cycling near the sediment/water boundary was investigated by measuring (1) SO4 2− reduction rates in the sediment, (2) depletion of SO4 2− in the overlying water column and (3) release of35S from the sediment into the water column. Two locations differing in sediment type (highly organic and sandy) were compared, with respect to reduction rates and depletion of SO4 2− in the overlying water. Sulfate reduction rates in sediments of an oligotrophic moorland pool were estimated by diagenetic modelling and whole core35SO4 2− injection. Rates of SO4 2− consumption in the overlying water were estimated by changes in SO4 2− concentration over time in in situ enclosures. Reduction rates ranged from 0.27–11.2 mmol m−2 d−1. Rates of SO4 2− uptake from the enclosed water column varied from −0.5, −0.3 mmol m−2 d−1 (November) to 0.43–1.81 mmol m−2 d−1 (July, August and April). Maximum rates of oxidation to SO4 2− in July 1990 estimated by combination of SO4 2− reduction rates and rates of in situ SO4 2− uptake in the enclosed water column were 10.3 and 10.5 mmol m−2 d−1 at an organic rich and at a sandy site respectively. Experiments with35S2− and35SO4 2− tracer suggested (1) a rapid formation of organically bound S from dissimilatory reduced SO4 2− and (2) the presence of mainly non SO4 2−-S derived from reduced S transported from the sediment into the overlying water. A35S2− tracer experiment showed that about 7% of35S2− injected at 1 cm depth in a sediment core was recovered in the overlying water column. Sulfate reduction rates in sediments with higher volumetric mass fraction of organic matter did not significantly differ from those in sediments with a lower mass fraction of organic matter.