Close to realistic responses to anti-cancer drugs are not adequately provided in monolayer or single cells assays. 3-dimensional multicellular cultures (spheroids) mimicking in vivo-like conditions are established as cell biological models for microtumors/metastases. For a non-invasive real-time monitoring of the electrical parameters of such spheroid cultures we designed, fabricated and tested a 3D multifunctional electrode-based microcavity array. In a non-adherent assay acute tests with tumor spheroids were done maintaining their spherical shape and cellular arrangement. The sensor chip with 15 individual square microcavities containing four gold electrodes each was used for impedance spectroscopy to analyze the tissue models in terms of morphological and structural changes. Cell type specific differences in the spectra and varying responses to several anti-tumor drugs were found. Further development of the prototype will provide a promising tool for the use in pharmacological high-throughput studies.