Neutron diffraction and ultrasonic velocity measurements have been car
ried out for molten Ag(Cl1-xIx) to investigate the local structure and
thermodynamic properties. In the structure factors for all concentrat
ions, the prepeak can be observed which suggests cluster formation of
halogen ions around a central cation. The temperature dependence of th
e adiabatic compressibility becomes larger for x = 0.57, where the mel
ting temperature has the lowest value. The concentration variations of
the structure factor and thermodynamic properties of this system are
discussed.