Despite the large number of experimental as well as theoretical investigations available in the literature, some properties of the hydration structure of Sr(II), for example, the coordination number, are still ambiguous. The presented molecular dynamics study based on a most suitable ab initio QM/MM protocol allowed a detailed investigation of structural and dynamical properties of this hydrate, which shows a considerable degree of internal flexebility as well as ligand mobility within the first shell. Despite the high computational effort an exceptionally long QM/MM simulation had to be carried out to obtain sufficient information to investigate first shell ligand exchange reactions.