Structural and dynamical properties of the hydration of K+ and Na+ ions have been investigated at atomistic level of detail by molecular dynamics simulations of the ion and 253 water molecules with periodic boundary conditions at the temperatures of 300 and 450 K. The intermolecular interactions involved have been modelled by a recently developed approach targeted to accuracy and low computational cost. Radial distribution functions and coordination numbers have been obtained to assess overall reliability of the model. Two different types of water models, rigid and flexible, have been used in simulations, evaluating the effect of adding flexibility to water.