Preface (N.G. Adams, L.M. Babcock). Ion-molecule chemistry in interstellar clouds: successes and problems (E. Herbst). Complex formation in electron-ion recombination of molecular ions (R. Johnsen, J.B.A. Mitchell). Reactive probing of the potential energy surfaces of isomeric ions (N.G. Adams, N.D. Fisher). Dynamics of gas-phase SN2 nucleophilic substitutional reactions (W.L. Hase et al.). Barriers to internal rotation in substituted toluenes and their cations: effects of electronic excitation and ionization (E.C. Richard et al.). The influence of solvation on ion-molecule reactions (A.W. Castleman Jr). Thermochemistry of singly and multiply charged ions produced by electrospray (J.S. Klassen et al.). Positive ion-electron impact ionization cross sections: theory and experiment (P.W. Harland, C. Vallance). Index.