The complexes AsX(3) . nL (where L is 2,6-dimethylaniline(dimean), o-, m- or p-chloroaniline (o-, m- or p-chloran), n = 1, 3/2, 5/2 or 3, and X is Cl, Br or I) were synthesized and characterized by melting points, elemental analysis, TG and DTG analysis, mass spectra and IR spectroscopy. From the enthalpies of dissolution in 25% (v/v) ethanolic ethanolamine and using appropriate thermochemical cycles, the following thermochemical parameters for the adducts have been determined : the standard enthalpies for the Lewis acid/base reaction (Delta(r)H(circle minus)), the standard enthalpies of formation (Delta(f)H(circle minus)), the standard enthalpies of decomposition (Delta(D)H(circle minus)), the lattice standard enthalpies (Delta(M)H(circle minus)), and the enthalpies of the Lewis acid/base reactions in the gaseous phase (Delta(r)H(circle minus)(g)). The mean standard enthalpies of the arsenic-nitrogen bonds have been estimated.