Cu(CTH9N)2(C12H8N2)(H20)](C104)2, M r =675.0, triclinic, P1, a=9.391 (2), b= 12.457 (2), c=13.448(3)A, a=74.81(2), fl=87.95(2), y= 79.46 (1) °, V= 1492.5 (7) A 3, Z= 2, Ox= 1.50gcm -3, 2(MoKa)=0.71073A, fl=9.7cm -1, F(000) = 694, T= 293 K, R = 0.040 for 3783 unique observed reflections. The four N atoms which are planar to within 0.020 (3) A and the O of the water molecule give rise to a square-pyramidal coordination geometry about the Cu atom, which is 0.237 (1)A above the basal plane. The planes of the two 3,5dimethylpyridine rings form dihedral angles of 83-3 and 110.5 o with the N-atom plane.