A Monte Carlo simulation of Fe2+ aqueous solvation, at 298 K, including 100 water molecules, has been done using periodic boundary conditions under the minimum image conversion. The energy has been calculated in the pair-potential approach, employing the MCY potential for the H2OH2O interaction and an ab initio analytical potential generated by us for the Fe2+H2O interaction. The examination of interaction energies and of the radial distribution functions clearly show that the first hydration shell is formed by eight water molecules. By classifying the generated configurations into different significant structures of the solvent, it has been found that the eight water molecules of the first hydration shell are situated in a lightly distorted D4d structure which maximizes the water-solute stabilization and minimizes the water-water repulsion. Finally, the validity of our theoretical predictions is discussed. © 1987.