This dataset provides the rawdata of an extensive microthermometric study of fluid inclusions in hydrothermal precipitates recovered at Brothers volcano. Samples originate from the NW Caldera and the Upper Caldera vent sites and were retrieved during RV Sonne cruise SO253 in December 2016/January 2017 and during RV Thompson cruise TN350 in March 2018. The dataset contains >400 single measurements of ice melting temperatures, >340 measurements of homogenization temperatures and includes a detailed descriptions of the measured fluid inclusions.