In the present study, the surface tensionSurface tension of sulfurSulfur-containing manganeseManganese-boron steelsSteel is measured at high temperaturesHigh temperature via the Maximum Bubble Pressure (MBPMaximum Bubble Pressure (MBP)) method. Density, essential for determining surface tensionSurface tension, was measured in parallel and found to decrease slightly with rising temperatures, from 6952 ± 13 to 6830 ± 85 kg m−3 between 1550 and 1650 ℃, as seen in the alloy containing 130 ppm S. Surface tensionSurface tension in this alloy increased from 1234 ± 4 to 1301 ± 9 mN m−1 as the temperature increased from 1550 to 1650 ℃, with a consistent positive temperature coefficient. Even small additions of sulfurSulfur significantly reduced surface tensionSurface tension at all temperatures. For instance, at 1600 ℃, the surface tensionSurface tension decreased from 1389 to 1264 mN m−1 with the increase of sulfurSulfur from 39 to 130 ppm. The relationship between surface tensionSurface tension and sulfurSulfur content followed an inverse logarithmic relationship and the temperature increase decreased the coefficient of change of the surface tensionSurface tension. This work generated reliable results, contributing to the understanding of surface tensionSurface tension and providing data for the processing of this steelSteel grade.