The data is a first digital release of the UK legacy geothermal catalogue of temperature measurements, thermal conductivity measurements and heat flow calculations. The geothermal catalogue comprises data contained in numerous historic technical reports from the 1977-1991 Geothermal Energy Programme, delivered by BGS and funded by the then UK Department of Energy and the European Commission. This release contains 11,821 data points derived from 743 sites. This first digital release contains data that has been: spatially located, an identified data source, intellectual property rights (IPR) checked and assessed for release under version 3 of the Open Government Licence (OGL). There are known limitations on the dataset, including that the data is provided as it was listed in the UK legacy geothermal catalogue. Validation of the IPR and copyright status of some of the incorporated datasets was challenging and a take down policy is in operation. Further details can be found in the accompanying report https://nora.nerc.ac.uk/id/eprint/537202