The Layered Structure of Cu2(H2O)4[C4H4N2][C6H2(COO)4]·2H2OTriclinic single crystals of Cu2(H2O)4[C4H4N2][C6H2(COO)4]·2H2O have been grown in an aqueous silica gel. Space group (Nr. 2), a = 723.94(7) pm, b = 813.38(14) pm, c = 931.0(2) pm, α = 74.24(2)°, β = 79.24(2)°, γ = 65.451(10)°, V = 0.47819(14) nm3, Z = 1. Cu2+ is coordinated in a distorted, octahedral manner by two water molecules, three oxygen atoms of the pyromellitate anions and one nitrogen atom of pyrazine (Cu—O 194.1(2)–229.3(3) pm; Cu–N 202.0(2) pm). The connection of Cu2+ and [C6H2(COO)4)]4− yields infinite strands, which are linked by pyrazine molecules to form a two-dimensional coordination polymer. Thermogravimetric analysis in air showed that the dehydrated compound was stable between 175 and 248 °C. Further heating yielded CuO.