The treatment of soil with SO2caused rapid increases in concentrations of water soluble plus exchangeable (extractable) Mn. The extractable Mn increased with increasing pressure of SO2and time of exposure, and increased with increasing water contents up to field capacity but decreased beyond this point. The addition of peat to a sandy loam increased the effect of SO2on extractable Mn while the addition of lime decreased the effect. Reactive Mn oxides in soils may contribute significantly to SO2sorption by soils.