Dirac-Hartree-Fock (DHF) calculations were performed to investigate the hydration of the trivalent Cm ion with a 5f(7) configuration on the models of Cm(H2O)(n)(3+) (n=1,2,4,6). The curium-oxygen distances and stabilization energies were evaluated. The DHF wave functions were analyzed by the Mulliken populations and spinor projections. Hydration was found to be characterized by the coordinate bond. An increase in the number of water molecules caused an increase in the curium-oxygen distance and a reduction of the stabilization energy per water molecule. The fluorescence transition energy was also estimated using the complete open-shell configuration interaction (COSCI) method. Redshifts due to hydration were obtained and were in accord with observations of the nephelauxetic effect. The isovalent gadolinium ion Gd3+ was also studied for comparison.