We studied using x-ray photoelectron spectroscopy the deposition of Au, In, Ag and Al overlayers onto clean-cleaved GaTe(001) surfaces at room temperature. The first steps of the Schottky barrier formation on Au and In showed no interface reactions. Free Te release was observed after the deposition of 3.5 Angstrom of silver. On the other hand, the deposition of Al leads to an exchange chemical reaction where clustering dominates at high metal coverage.