The ground state potential energy surface of the (N2O . H2O)(+) cluster cation is explored with ab initio and density functional theories. B3LYP optimizations are used to determine the structure of the products of the dissociation of the cluster ions as well as possible structures for the clusters themselves and transition states that connect various minima. Energetics for all optimized structures are determined with the G2M(RCC,MP2) method. The results are used to interpret collision-induced dissociation (CID) experiments which study the cluster ion, and which find that the cluster dissociates to form H2O++N2O, N2OH++OH, and N2O++H2O products. The calculations an (N2O-OH2)(+) complex as well as a similar (H2O-N2O)(+) complex, and show that these complexes access the experimentally observed H2O++N2O products and N2OH++OH products without any intervening reverse barrier. The stability of both these complexes, approximately -20 kcal/mol relative to the H2O++N2O products, agrees well with experimentally determined CID thresholds for all products. Additional calculations of the ground state potential energy surface of the cluster investigate the possibility of the formation of other products. Some preliminary studies of the excited states of the cluster cation are also performed; the results of these calculations lend insight into experimental photodissociation studies of the cluster ions. Mechanisms for the formation of H2O++N2O, N2OH++OH, and N2O++H2O products following photoexcitation of the cluster ions are discussed; the H2O++N2O and N2OH++OH products must be formed from a surface-hopping from an excited electronic state to states which correlate to ground state products. Similarly, N2O++H2O products may be formed from collision induced dissociation of clusters only by means of a surface-hopping mechanism.