FeCoZr magnetic alloy films were electrodeposited on ITO conductive glass from sulfate baths with different thiourea concentration. The composite, structure and magnetic properties of FeCoZr films were investigated as a function of thiourea concentration. The sulfur content of the films increases almost linearly with increasing thiourea concentration. All thin films have crystalline texture with (110) plane parallel to the film plane. As thiourea concentration increases from 0.5 to 4.0 g/L, films coercivity increases from 19 to 56 Oe, the squareness ratio decreases from 0.74 to 0.15. The natural resonant frequency (f(r)) of films linearly increase from 0.35 to 2.00 GHz with the increasing of thiourea concentration in the bath. It has been proved to be a new way to adjust the resonant frequency of soft magnetic material for high frequency application. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.004211jes] All rights reserved.