A layered mercury telluride, Rb2Hg3Te4, was discovered during an exploration of hydro(solvo)thermal synthesis of tellurides at temperatures somewhat above the boiling point of ethylenediamine. Crystals of Rb2Hg3Te4 were grown from solvothermal reactions using ethylenediamine as a solvent. Single crystal X-ray diffraction analysis shows that this compound belongs to the orthorhombic system, space group Pbcn (No. 60) with lattice parameters a=12.177(2) Angstrom, b=7.245(2) Angstrom, c=14.545(2) Angstrom, and Z=4. The structure contains two-dimensional layers of (2)(infinity)[Hg3Te42-] which are separated by the Rb+ counterions. The interlayer Te-Te distances imply weak van der Waals interactions. Rb2Hg3Te4 is the first two-dimensional mercury telluride prepared by an unconventional low-temperature technique.