The compounds SnBr4. nL (where L is urea (u), 1,1-dimethylurea (1,1-dmu). 1,3-dimethylurea (1,3-dmu), tetramethylurea (tmu), thiourea (tu), tetramethylthiourea (tmu) or 1-allyl-2-thiourea (atu) and n = 2, 3 or 4) were synthesized and characterized by melting points, elemental analysis, thermal analysis and IR spectroscopy. The enthalpies of dissolution of the adducts, tin(IV) bromide and ligands in methanol were measured and by using thermochemical cycles the following thermochemical parameters for the adducts have been determined: the standard enthalpies for the Lewis acid/base reaction (Delta H-r(0)); the standard enthalpies of formation (Delta H-f(0)) the standard enthalpies of decomposition (Delta H-D(0)); the lattice standard enthalpies (Delta H-M(0)) and the standard enthalpies of the Lewis acid/base reaction in the gaseous phase (Delta H-r(0)(g)). The mean standard enthalpies of the tin-oxygen ((D) over bar ((Sn-O))) and tin-sulphur ((D) over bar ((Sn-S))) bonds have been estimated.