In the title complex, [Ni(C₆H₆N₃O)(NCS)(C₆H₇N₃O)(H₂O)] or [Ni(mpko)(SCN)(mpkoH)(H₂O)] [where mpkoH = 1-(pyrazin-2-yl)ethanone oxime], the Ni(II) cation is in a slightly distorted octa-hedral geometry, being coordinated in the equatorial plane by four N atoms from two different mpkoH ligands, one of which is deprotonated, and by one N atom from a thio-cyanate anion and one O atom from a water mol-ecule in the axial positions. There is an intra-molecular O-H⋯O hydrogen bond involving the oxime units of the two ligands. In the crystal, a three-dimensional supra-molecular architecture is formed by O-H⋯O and O-H⋯N hydrogen bonds.