AbstractAu/TiO2 nanorod composites with different ratios of [TiO2]:[Au] have been prepared by chemically reducing AuCl4‐ on the positively charged TiO2 nanorods surface and used to modify boron‐doped diamond (BDD) electrodes. The electrochemical behaviors of catechol on the bare and different Au/TiO2 nanorod composites‐modified BDD electrodes are studied. The cyclic voltammetric results indicate that these different Au/TiO2 nanorod composites‐modified BDD electrodes can enhance the electrocatalytic activity toward catechol detection, as compared with the bare BDD electrode. Among these different conditions, the Au/TiO2‐BDD3 electrode (the ratio of [TiO2]:[Au] is 27:1) is the most choice for catechol detection. The electrochemical response dependences of the Au/TiO2‐BDD3 electrode on pH of solution and the applied potential are studied. The detection limit of catechol is found to be about 1.4 × 10‐6 M in a linear range from 5 × 10‐6 M to 200 × 10‐6 M on the Au/TiO2‐BDD3 electrode.