From june 2nd to 5th 1980, the vth international symposium on solute-solute-solvent interactions was held in florence, italy. owing to the large range of interests included in the program and to their interdisciplinary nature, a number of microsymposia on specific subjects were organized, in addition to plenary lectures, session lectures and poster sessions. the abstracts of the confer­ ence were published in inorganica chimica acta as a special publi­ cation and as an appendix to the issue of june 1980. the plenary lectures have been published, as customary, in the journal of pure and applied chemistry (october 1980) and the results of the following microsymposia are being published in specialized journals: 1) electronic rearrangements induced by solute-solvent interactions (local editor j. h. ammeter) - ~. i. phys. chimie. 2) anion activation in quaternary salts, crown ethers, cryptates and related systems (local editor f. montanari) - i. mol. catalysis. 3) solvent effects in homogeneous catalysis by metal complexes (local editor r. ugo) - i. mol. catalysis. 4) theoretical models in biochemical and related systems (local editor e. clementi) -~. computational chemistry. 5) thermodynamic approach in coordinative interactions in solution (local editor p. paoletti) - advances in molecular relaxation and interaction processes.