Although the melt structure of glass-forming ZnCl2 has so far been well studied, there exists quite little information on the structural change due to anion-substitution. In the present work, the short-range structure of ZnCl2-ZnBr2 mixture melts was analyzed systematically by time-of-flight pulsed neutron diffraction techniques, Raman spectroscopy, molecular orbital calculations, and molecular dynamics simulations. According to radial distribution analysis, it was found that there were tetrahedral structural units of ligand-substituted [ZnClnBr4-n](2-) (n=0-4) in these melts, not implying the simple mixing of [ZnCl4](2-) and [ZnBr4](2-) units. Further detailed estimation indicated that the ligand-substituted complex anions were linked with each other by sharing a common anion. (C) 2004 Elsevier Ltd. All rights reserved.