The title compound, diaqua-1kappaO,3kappaO-di-mu-hydroxido-1:2kappa(2)O:O,2:3kappa(2)O:O-di-mu-methacrylato-1:2kappa(2)O:O',2:3kappa(2)O:O'-bis(1,10-phenanthroline)-1kappa(2)N,N';3kappa(2)N,N'-tricopper(II) dinitrate dihydrate, [Cu(3)(C(4)H(5)O(2))(2)(OH)(2)(C(12)H(8)N(2))(2)(H(2)O)(2)](NO(3))(2) x 2 H(2)O, has the central Cu atom on an inversion centre. The three Cu(II) atoms are in a linear arrangement linked by methacrylate and hydroxide groups. The coordination environments of the Cu(II) ions are five-coordinated distorted square-pyramidal for the outer Cu atoms and four-coordinated square-planar for the central Cu atom. All nitrate ions, hydroxide groups and water molecules are linked by hydrogen bonds, forming a linear structure. The complex exhibits ferromagnetic exchange coupling, which is helpful in elucidating magnetic interactions between copper ions and other metallic ions in heteronuclear complexes.