Data sets contain the osmium isotope information of the limestone samples from the Fiume Bosso section (43°31'07.2N 12°34'15.4E), central Italy. Os isotopic analysis was conducted in August 2021 to reconstruct paleo-marine Os and carbon isotopic variation. Os were separated by the weak-leaching method (1M HCl) and Os isotopic ratios were measured with thermal ionization mass spectrometry (TRITON, Thermo Fisher Scientific, USA). Our Os data covers the time ranges from the upper Hauterivian to the lower Barremian of the Lower Cretaceous.

The data includes Os and Re concentrations and measured (present-day) and initial (age-corrected) osmium isotopic ratios (187Os/188Osm and 187Os/188Osi) of limestone samples acquired from the Fiume Bosso section. Os was separated from the limestone samples using weak-leaching methods.