The title nickel(II) complex, [NiCl2(C18H15OP)2], was prepared in order to determine the coordination of the Ni atom. The Ni atom lies on a twofold axis and is four-coordinated by two Cl atoms and two O atoms in a distorted tetrahedral coordination geometry. The Ni—Cl and Ni—O distances are 2.2151 (6) and 1.9662 (16) Å, respectively. The title compound is compared with the four-coordinated copper(II) analog; the two systems are isostructural.