Included in this dataset are measurements of the volatile organosulfur compounds methanethiol (MeSH), dimethyl sulfide (DMS), and dimethylsulfoniopropionate (DMSP) that were measured in ferruginous and sulfidic sediments collected in the Warham Salt Marsh in north Norfolk, UK, in 2016-2017. Data include measurements of DMS and MeSH in homogenized marsh sediments (vosc_homogenized_sediments.csv) treated with various sediment amendments and analyzed using a cryotrapping gas chromatograph at the University of York. There are also measurements of DMS and MeSH for depth profiles of unamended sediments (vosc_depth_profiles.csv) analyzed using GC-FID at the University of East Anglia. There are also measurements of DMSP for these sediments (dmsp_depth_profiles.csv). Finally, concentrations of both DMS and MeSH for sediments measured at different times after sampling are reported (vosc_time_degradation.csv). For all reported values, they are reported both as the measured headspace concentration above slurried sediment as well as the calculated total amount of gas (nmol) in the headspace and added water per ml of sediment that was sampled.