This data publication contains the compilation of global heat-flow data by the International Heat Flow Commission (IHFC; http://www.ihfc-iugg.org/) of the International Association of Seismology and Physics of the Earth's Interior (IASPEI). The presented data release 2021 contains data generated between 1939 and 2021 and constitutes an updated and extended version of the 2012 IHFC database release (IHFC 2012; later re-published as PANGAEA release: Global Heat Flow Compilation Group, 2013). The 2021 release contains 74,548 heat-flow data from 1,403 publications. 55% of the reported heat-flow values are from the continental domain (n ~ 40,870), while the remaining 45% are located in the oceanic domain (n ~ 33,678). The data are provided in csv and Excel formats. Compared to earlier compilations, which followed the structure defined by Jessop et al. (1976), the new data release was transformed to the recently redefined structure for reporting and storing heat-flow data in the Global Heat Flow Database (Fuchs et al., 2021). Therefore, the notation and structure of the database was adopted, transforming the database field entries defined after Jessop et al. (1976) to the new field structure. Old code notations are not continued and the dataset was cleaned for entries without reporting any heat-flow value. Although successfully transformed, this release marks an intermediate step as the majority of the newly defined database fields have not been filled yet. Filling these fields, checking the existing entries and assessing the quality of each entry are the aim of the upcoming Global Heat Flow Data Assessment Project, for which this data set provides the basis. Consequently, we kindly ask the user to take notice that the current release still suffers similar problems as previously published compilations in terms of data heterogeneity, documentation and quality.