Abstract A new neutral mononuclear nickel(II) complex of the composition [Ni(Me2iz)2(ac)2] was prepared and characterised (Me2iz=1,2-dimethylimidazole, ac=acetate). The X-ray structure analysis shows that the carboxylato group coordinates as a bidentate ligand with a low O–Ni–O angle of 62°. Therefore an enhanced magnetic anisotropy is expected and confirmed by the magnetic susceptibility measurements. The set of magnetic parameters is gx,gy=2.175, gz=2.263, D/hc=−14.30 cm −1 , and χ TIP =2.04×10 −9 m 3 mol −1 . The axial zero-field splitting parameter D spans the interval of large values owing to a combined effect of the ligand field and angular momentum anisotropy.