The new compound Hg similar to 2.8KMo12S14, was synthesized by diffusing mercury into the metastable KMo(12)s(14) compound at 350(circle)C. Its crystallographic structure, solved from single-crystal X-ray diffraction, shows that the Mo-S framework is maintained during the synthesis. It is based on Mo12S14S6 units interlinked via Mo-S bonds as in the parent compound. The mercury forms linear chains with Hg-Hg distances of about 2.72 A in the tunnels delimited by the Mo12S14S6 units. Superconductivity was observed below 2.5 K by electrical resistivity and magnetic susceptibility measurements.