We investigated the etch characteristics of Ba(Mg1/3Ta2/3)O-3 (BMT) films using Cl-2/SF6 gas mixtures with electron cyclotron resonance plasma. The etch rate in pure Cl-2 gas plasma was approximately 1250 Angstrom/min and was decreased by the addition of SF6. By quadrupole mass spectrometer analysis, we found that the etch rate had a close relationship to the Cl radical. The surface reaction on the BMT films during the etch was examined by X-ray photoelectron spectroscopy analysis. It is proposed that the BaClxOy compound has been formed by Cl-2 gas plasma. The chemical surface reaction and BMT etch characteristics with SF6/Cl-2 gas chemistries are discussed in detail.