The thermofacies concept is based on new measurements of about 11 000 plug samples drilled from sedimentary rocks and investigated at TU Darmstadt from 2007 to 2011. Some hundred representative thin sections were analysed for facies interpretation. The thermofacies concept was developed for low and mid enthalpy geothermal systems linked to graben settings and deep sedimentary basins located in Central Europe. The understanding of the spatio-temporal development of sedimentary facies within a specific geothermal exploration area may contribute to establish integrated structural 3D reservoir models. Thus, thermofacies – the facies dependence of geothermal parameters – become a key feature for reservoir prognosis, reservoir stimulation and efficient reservoir utilization.