Sheet Rb 2 HgSnS 4 was synthesized solvothermally and characterized by X-ray single crystal diffraction. The compound is comprised of sheets with admantane-like [Hg 2 Sn 2 S 10 ] 8– units. The crystals belong to the space group C 2 /c, with the unit cell parameters a=1.1063(2) nm, b=1.1071(2) nm, c=1.5741(3) nm, a=90º, β=100.13(3)º, γ=90º. A reflectance spectroscopy study reveals the nature of the semiconductor with an energy of 2.1 eV for the compound.