The thermal behavior of the short-range order of Pd40Cu30Ni10P20 bulk metallic glasses has been investigated in situ by means of hightemperature X-ray synchrotron diffraction. The dependence of the X-ray structure factor S(q) of the glassy state on temperature follows the Debye theory up to the glass transition. Above the glass transition temperature T-g, the temperature dependence of S(q) is altered toward a continuous development of structural changes in the liquid state with temperature. The behavior of the structure factor during heating and cooling through the glass transition gives experimental evidence for melting the glass, and for freezing the liquid, respectively at the caloric glass temperature. (c) 2007 Elsevier BN. All rights reserved.