A computational experiment aimed to create and systematically analyze models of simple cation hydrates is presented. The changes in the structure (bond distances and angles) and the electronic density distribution of the solvent and the thermodynamic parameters of the hydration process are calculated and compared with the experimental data. The influence of the ion charge and size on the interaction of simple cations with water molecules is discussed. Both the physical implications of the results and the internal consistency of the theoretical models employed are discussed, offering a good first approach to the theoretical study of interesting systems, such as those that result from the interaction of simple ions with the solvent. (Contains 3 tables, 2 figures, and 3 notes.)