The thermochemical properties of some small clusters such as the (H2O)(2)(center dot+) dimer have already been investigated by both experimental and theoretical methods. The recent method to selectively prepare the ammonia-water ionized dimer [NH3, H2O](center dot+) (and not its proton transfer isomer [NH4+, OHcenter dot]) allowed us to study its chemical reactivity. This study focuses on the charge and proton transfer pathways: Ion-molecule reactions in the cell of an FT-ICR mass spectrometer were carried out with a range of organic compounds. Examination of the reactivity of the [NH3, H2O](center dot+) ionized dimer versus ionization energy and proton affinity of the neutral reagents shows a threshold in the reactivity in both instances. This leads to a bracketing of thermochemical properties related to the dimer. From these experiments and in agreement with ab initio calculations, the adiabatic recombination energy of the [NH3, H2O](center dot+) dimer was evaluated at -9.38 +/- 0.04 eV. The proton affinity bracketing required the reevaluation of two reference gas-phase basicity values. The results, in good agreement with the calculation, lead to an evaluation of the proton affinity of the [NH2center dot, H2O] dimer at 204.4 +/- 0.9 kcal mol(-1). These two experimental values are respectively related to the ionization energy of NH3center dot+ and to the proton affinity of NH2center dot by the difference in single water molecule solvation energies of ionized ammonia, of neutral ammonia, and of the NH2center dot radical.