The title complex, [Li2(D2O)6][Li(C9H27SSiO3)2]2.2D2O, is the first compound with an S-M bond (M = alkali metal) within an unusual type of lithate anion, [Li(SR)2]- {where R is Si[OC(CH3)3]3}. There is a centre of symmetry located in the middle of the Li2O2 ring of the cation. All Li atoms are four-coordinate, with LiO4 (cations) and LiO2S2 (anions) cores. The singly charged [Li(SR)2]- anions are well separated from the doubly charged [Li2(D2O)6]2+ cations; the distance between Li atoms from differently charged ions is greater than 5 A. Both ion types are held within an extended network of O-D...O and O-D...S hydrogen bonds.