In the title compound, [Ni(NCS)(2)(C(11)H(17)N(3))(H(2)O)], the Ni(II) ion is six-coordinated by the N,N',N"-tridentate Schiff base N atoms, two cis-positioned N-bound isothio-cyanate groups and one water mol-ecule. In the crystal, O-H⋯S hydrogen bonds link adjacent mol-ecules into infinite layers parallel to the ac plane. The layers are further connected into a three-dimensional network via C-H⋯π inter-actions. The -CH(2)-N(CH(3))(2) fragment is disordered over two sets of sites in a 0.556 (5):0.444 (5) ratio.