Four new triangular copper(II) complexes with the fragment {Cu₃(μ₃-OH)(oximate)₃}²⁺ and formulae [Cu₃(μ₃-OH)(μ-Cl)(Py₂CNO)₃(^tBuPO₃H)]·4H₂O (1), [Cu₃(μ₃-OH)(μ-Br)(Py₂CNO)₃(^tBuPO₃H)]·3.5H₂O (2), [Cu₃(μ₃-OH)(μ-Br)(PhPyCNO)₃(^tBuPO₃H)(MeOH)]·1.5 MeOH (3), [Cu₃(μ₃-OH)Cl₂(PhPyCNO)₃]·0.5H₂O (4), (Py₂CNO = di(2-pyridyl)ketoximate, PhPyCNO = phenyl(2-pyridyl)ketoximate, ^tBuPO₃H₂ = tert-butylphosphonic acid) are reported. The magnetic properties of compounds 1–4 were studied. The compounds were found to exhibit strong antiferromagnetic coupling and antisymmetric exchange interaction.