This dataset contains experimentally derived measurements of sulfur solubility and speciation in silicate melts, obtained over a temperature range of 1200–1500 °C and a pressure range of 1 bar to 2.5 GPa. The experiments were conducted as part of the NERC-funded project NE/W000660/1 “The chemical behaviour of sulphur in magmas at high temperature and pressure” (2022–2025). For each experiment, the dataset includes the experimental run ID, silicate melt composition, and the experimental conditions under which the run was performed: pressure, temperature, oxygen fugacity (fO?), sulfur fugacity (fS?), and run duration. The dataset also provides raw electron microprobe analyses (EMPA) for each experiment, expressed as elemental weight percentage averages. These analyses represent individual point analyses collected from polished epoxy resin mounts coated with carbon. Measurements were acquired using wavelength-dispersive spectrometry (WDS) on a standard-calibrated electron microprobe. The data are intended to support investigations into the behavior of sulfur in magmatic systems, including solubility mechanisms, redox speciation, and compositional controls on sulfur partitioning between melts and other phases. The data was acquired and analysed by the experimental petrology team, at the University of Oxford, Department of Earth Sciences