X-ray diffraction analysis reveals the thiogermanic acid H4Ge4S10 possesses discrete adamantane-like Ge4S104- complex anions. Each thioanion is composed of four corner shared GeS2.5- tetrahedral units. Crystals were grown from anhydrous liquid hydrogen sulfide reactions with glassy germanium sulfide at room temperature. The crystal structure was solved and refined from single crystal diffractometer data (Mo Kα radiation) obtained at 173 K. H4Ge4S10 is triclinic, centrosymmetric space group P1̄, with a = 8.621(4) Å, b = 9.899(4) Å,c = 10.009(4) Å, α = 85.963(7)°, β = 64.714(7)°, γ = 89.501(8)°, and Z = 2. Average bridging and terminal d̄(Ge−S) distances are 2.229 and 2.206 Å, respectively. Vibrational mode assignments are reported from Raman scattering and IR absorption spectra of polycrystalline samples. The νs(Ge−S−Ge) and νs(Ge−S-) stretching modes are observed at 354 and 405 cm-1, respectively.