We present here an EXAFS (extended x-ray absorption fine structure) experiment performed at the K edge of the sulfur atom of OCS isolated in an argon matrix. The aim was to elucidate the structure of the trapping site of the molecule. We show that the argon atoms are located at a mean distance of 3.78 Angstrom from the sulfur atom, with a root mean square variation of the S-Ar distances of about 0.08 Angstrom. Our results indicate that the host atoms occupy a statistical set of positions around the molecule, rather than well-defined sites.