Density-functional studies of titanium cation complexes with 6 and 18 water molecules were carried out. The charges +2, +3 and +4 were all considered. The lowest-energy minimum of the trivalent hexahydrated cation may have S-6 symmetry. The inclusion of the second coordination sphere leads to two geometrically distinct types of minima. Hydration energies of the Ti2+ and Ti3+ are calculated with 13-86 kJ/mol accuracy. The hydration energy of the Ti4+ ion is estimated at 7800 kJ/mol.