The performance of a curve-shaped capacitance sensor for measuring the mean liquid holdup of the two-phase mixture of gas-condensate and nitrogen in a vertical pipeline was studied experimentally. The sensor consists of two electrodes placed on the external wall of a cylindrical test duct. The calibration curves for bubble, slug, and plug flow regimes were developed for vertical flow and the sensitivity of the sensor to flow pattern was also investigated. Based on experimental observations, different calibration curves must be used for different flow regimes to have an acceptable accuracy in holdup measurement. Moreover, a new empirical correlation for estimating liquid holdup in vertical gas-condensate pipelines in the dynamic condition was developed as a function of superficial velocities, viscosities, and densities of the gas and liquid. Furthermore, a flow pattern identification map for vertical pipeline is also presented.