The reaction of trimethyltin (IV) chloride with tetrabutylammonium hydrogenosulphate leads to the formation of Bu4NHSO4.SnMe3Cl, the crystal structure of which has been determined by X-ray analysis. The structure consists of a discrete dimer, in which two hydrogen sulphate anions, each coordinated to a trimethyltin chloride moiety (SnMe3Cl) are held together by hydrogen bonds. The tin centre displays a trans OClC3 trigonal bipyramid configuration. Additional infrared, Mössbauer and NMR spectroscopic data are reported.