FeCl 3 ·6H 2 O was used in the wet etching of single crystalline ZnO films. The method has great effects on the suppression of the "W" shaped etching profile usually observed when ZnO films were etched by acid. "U" shaped profile and smooth surface morphology were obtained under a wide range of etching rate, as confirmed by stylus profiler and scanning electron microscopy. The ferric deposition detected by the X-ray photoelectron spectra is speculated to be responsible for the formation of suitable solution hydromechanical parameters. The deposited layers can be removed easily by ultrasonic treatment, which makes the process easily controllable. These results show that this method is promising for processing ZnO-based optoelectronic devices.