An electrical conductivity probe which provides a means of accurately measuring local void fractions in two-phase flow has been developed. The void fractions obtained with the probe in an air-water mixture agree with those calculated from flow rate data to within about ± 25% of the calculated value. However, an empirical modification of the current-void relationship brought this agreement to within ± 8% for void fractions ranging from 0.19 to 0.77.