Cassiterite (SnO2) samples were collected throughout Devon and Cornwall Counties in southwest England, United Kingdom. Samples were prepared and analyzed for direct age dating on a laser ablation inductively coupled plasma mass spectrometer (LA-ICPMS) system at the U.S. Geological Survey in Denver, Colorado in February and April 2018. This data release accompanies the publication, 'U-Pb geochronology of tin deposits associated with the Cornubian Batholith of southwest England: Direct dating of cassiterite by in situ LA-ICPMS' (Moscati and Neymark, 2018). The publication describes a greater chronologic control and refinement of Cornubian tin ore deposition and allows comparison of its timing with previously published ages for the granitic intrusions that host the cassiterite.