Measurement of void fraction of two-phase flows remains a challenging area. In this paper the application of an electrical resistance tomography (ERT) system for this purpose has been studied. A new approach through the direct use of the voltage data measured by the ERT system is presented. The measured voltage data are first compressed through a feature extraction, and a polynomial regression procedure is followed to obtain the relationship between the void fraction and the feature extracted. Both simulation and experiment are carried out to verify the approach. The methodology of the new approach, simulation and experimental results are presented in the paper.