BACKGROUND: Acquisition of electrical impedance spectroscopy (EIS) measurements enables one to obtain information about the features of cell cultures, which can be applied for real-time and on-linemonitoring purposes. RESULTS: Impedance measurements were carried out in three different cell specimens with different sizes and shapes (Vero cells, hybridoma and Escherichia coli) at different stages of cell culture, as well as during a controlled detachment process of an adherent animal cell line. The relaxation spectra obtained were fitted to a Cole impedance model and the corresponding parameters analyzed. The use of a four-electrodes measurement system decreased the dependency on the electrode interface’s impedance, and thus resulted in a systemmore sensitive to the cell features. The EISmonitoring of different cultures expansion showed the expected inverse proportional relationship between the central relaxation frequency and the cell cross-sectional area. The morphological changes of fibroblast cells during the detachment processes were also studied. Interestingly, EIS displayed the proportional relationship between the ¿ parameter of the Cole impedance model and the cell shape dispersion from sphericalmorphology (considering spherical shape ideality). CONCLUSION: The results obtained reveal the potential for developing a real-time monitoring tool for cell morphology features such as cell size and shape, which are involved inmany cellular processes like cell expansion, differentiation, cell attachment or cell death.