One double chains nickel(II) coordination polymer has been synthesized and characterized in the solvent mixture of water and methanol with 3,5-dimethylbenzole acid, 4,4'-bipyridine and nickel perchlorate anhydrous. Crystal data for this complex: Triclinic, space group P (1) over bar, a=1.13449(12) nm, b=1.137 81(12) urn, c=1.238 25(13) rim; alpha=100.374 0(10)degrees, beta=109.481 0(10)degrees, gamma=101.403 0(10)degrees, V=1.423 8(3) nm(3), D-c=1.314 g.cm(-3), Z=1, F(000)= 592, final GooF=1.029, R-1=0.0396, wR(2)=0.1064. The complex involves two solvent molecules, two waters or two methanols....