Visual differentiation of lower grade glioma tissue from normal brain tissue during surgery is difficult even for expert neurosurgeons. Therefore, during tumour removal neurosurgeons rely on image guidance. It has been proven that higher rates of tumour resection prolong long-term survival of patients. We aim to implement impedance spectroscopy as a potential supportive tool to improve radical resection. During this pilot study, we evaluated the possibility to differentiate ex vivo tissue samples (biopsy samples during tumour surgeries) with the help of impedance spectroscopy. Tissues were collected from two patients and impedance spectra differences were found between low-grade glioma, high-grade glioma and healthy brain tissue.