The hydrothermal reactions of Ni(II), 1,2,3-benzenetricarboxylic acid (1,2,3-H(3)btc) and 4,4'-bipyridine (4,4'-bpy)/1,2-bis(4-pyridyl)ethane (bpa) yield two layered nickel(II) coordination polymers, [Ni(2)(1,2,3-btc)(OAc)(4,4'-bpy)(2)(H(2)O)]center dot 2H(2)O (1) and [Ni(ip)(bpa)] (2) (ip= isophthalate), respectively. Both complexes are 2-D coordination network based on 1-D Ni-carboxylate chains. The 1,2,3-btc ligand adopts 3-bridging mode in complex 1, but transformed to isophthalate (ip) ligand through decarboxylation in 2. The formation of the two complexes indicates that hydrothermal conditions and in-situ ligand reaction have significant effect on constructing coordination polymers.