The geometries of various structures of [Ge,X,H-3](+) (X = O, S) have been optimized by using the HF/3-21G(*) and MP2/3-21G(*) methods and their vibrational frequencies computed. Electron correlation errors are corrected up to the MP4SDTQ level. It has been shown that the X-protonated state of H(2)GeX (X = O, S) is more stable than the Ge-protonated one. At the MP4SDTQ/3-21G(*)//MP2/3-21G(*) + ZPE level, H-2-GeO and H2GeS have been computed to have respectively X-site proton affinities of 197.4 and 188.4 kcal mol(-1), which are attributable to the different charge separations of their double bonds. The 1,2-hydrogen shift reaction of H(2)GeXH(+) to HGeXH(2)(+) is exothermic with a barrier of 50.9 kcal mol(-1) for X = O but endothermic with a barrier of 52.9 kcal mol(-1) for X = S, with transition-state structures as expected from Hammond’s postulate.