Herein, an electrochemical sensor for sensitive and simple determination of Cd 2+ was fabricated based on the excellent properties of acetylene black (AB) and strong inducing adsorption ability of I − . In pH 3.6 HAc–NaAc buffer containing 5.0×10 −3 molL −1 I − , Cd 2+ was induced to accumulate at AB paste electrode surface under the inducing adsorption of I − , and then reduced to Cd at −1.10V. During the following potential sweep from −1.10 to −0.40V, reduced Cd was oxidized, resulting in a sensitive and well-shaped stripping peak at −0.83V. Based on this, a new electrochemical method was developed for Cd 2+ analysis. The linear range is found to be 5.0×10 −8 to 2.0×10 −6 molL −1 , and the detection limit is 2.0×10 −8 molL −1 . Finally, this sensor was successfully used to detect Cd 2+ in water samples.