Synthesis of the new fulleride HgxC60 Was achieved inside an evacuated ampoule filled with metallic Hg and C-60 powder kept at 500 degrees C for several months. A heat capacity anomaly is observed at 232.3 K, reminiscent of the ordering transition of pristine C-60 but With reduced transition enthalpy. Weakly shifted F-1u infrared bands suggest lack of Hg-C-60 charge transfer. The structure at 300 K is as in pristine C-60 but with a measurable lattice expansion consistent with Hg intercalation in octahedral sites. This lattice expansion induces downshift of the ordering transition and weak displacement of infrared bands. (C) 2000 Elsevier Science B.V. All rights reserved.