Copper(II) complexes of the following polyimidazole ligands have been synthesized : bis(imidazol-2-yl)methane (BIM), bis(imidazol-2-yl) ketone (BIK), 4-(imidazol-4-ylmethyl)-2-(imidazol-2-ylmethyl)imidazole (TRLM), bis-[4-(imidazol-4-ylmethyl)imidazol-2-yl]methane (TIM), and bis[4-(imidazol-4-ylmethyl)imidazol-2-yl] ketone (TIK). Their crystal structures have been determined using X-ray diffraction. [Cu(ClO4)(2)(BIM)(2)], 1, belongs to the triclinic space group P (1) over bar system, a = 7.161(4) Angstrom, b = 7.986(6) Angstrom, c = 9.865(3) Angstrom, alpha = 76.73(5)degrees, beta = 71.1.8(3)degrees, gamma =176.44(5)degrees Z = 1, T = 291 K; R = 0.035, R-w = 0.036 for 1668 reflections; Cu-N = 1.998(3) and 2.001(2) Angstrom, Cu-O = 2.574(4) Angstrom, in a tetragonal geometry. [Cu(BIK)(2)](ClO4)(2), 2, belongs to the monoclinic space group C2/c system, a = 9.029(3) Angstrom, b = 12.497(2) Angstrom, c = 19.197(2) Angstrom, beta = 94.59(2)degrees, Z = 4, T = 291 K; R = 0. 056, R-w = 0.061 for 1052 reflections; Cu-N = 1.961(7) and 1.954(7) Angstrom, in a distorted tetrahedral geometry. [CuCl-(TRIM)(CH3OH)]Cl, 6, belongs to the monoclinic space group P2(1)/n system, a = 14.192(5) Angstrom, b = 13.832(5) Angstrom, c = 7.913(3) Angstrom, beta = 90.55(4)degrees, Z = 4, T = 291 K; R = 0.062, R-w = 0.057 for 1377 reflections; Cu - N = 1.987(7), 2.007(7) and 2.007(6) Angstrom, Cu-O = 2.521(7) Angstrom, Cu-Cl = 2.298(2) Angstrom, in a square pyramidal geometry.