The X-ray structure of [Pt{HN=C(O)Bu(t)}(2)(H2O)2] has shown that water oxygen exerts a smaller ground state trans-influence than amine nitrogen. Very strong H bonds link cis amidato and water ligands [O...O = 2.484(6) Angstrom, O-H...O = 150(8)degrees] and cause an in-plane plane orientation of the amidato ligand [dihedral angle of 7.7(2)degrees]. Analogous interactions between cis amidato and amine ligands appear to be significantly weaker.