This data set contains intraoperative electrocorticography (ioECoG) data from 91 patients collected during epilepsy surgery performed in the University Medical Center Utrecht, the Netherlands. It is made public as supplementary data to support the findings of the manuscript by Hoogteijling et al. (2024) entitled 'Machine learning for (non-)epileptic tissue detection from the intraoperative electrocorticogram', published in Clinical Neurophysiology. Please cite this article in any project using this data set. See also: github.com/UMCU-EpiLAB/umcuEpi_explainable_AI