This paper presents the characteristics of a double helix capacitance sensor for measurement of the liquid holdup in horizontal oil-water two-phase flow. The finite element method is used to calculate the sensitivity field of the sensor in a pipe with 20 mm inner diameter and the effect of sensor geometry on the distribution of sensitivity field is presented. Then, a horizontal oil-water two-phase flow experiment is carried out to measure the response of the double helix capacitance sensor, in which a novel method is proposed to calibrate the liquid holdup based on three pairs of parallel-wire capacitance probes. The performance of the sensor is analyzed in terms of the flow structures detected by mini-conductance array probes. (C) 2014 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.