Two novel ladder-like copper(II) compounds, [Cu 2 (histamine) 2 (C 2 O 4 )(ClO 4 ) 2 ] (1) and [Cu 2 (histamine) 2 (C 2 O 4 )(H 2 O) 2 (NO 3 ) 2 ] (2), are prepared. Compound 1 crystallizes in the triclinic space group P1, with a=7.450(4) Å, b=7.519(7) Å, c=9.646(5) Å, α=85.78(7)°, β=88.60(4)°, γ=76.78(7)°, V=524.5(6) Å 3 , and Z=1 with R=0.0789 (all data). In 1, the dinuclear units of [Cu 2 (histamine) 2 (C 2 O 4 )] 2+ are linked together by the perchlorate anions to form a ladder-like chain. The chains interact each other by the π–π stacking interactions via the imidazole groups. Compound 2 crystallizes in the triclinic space group P1, with a=7.579(2) Å, b=8.133(1) Å, c=9.161(3) Å, α=77.06(2)°, β=89.23(2)°, γ=82.54(1)°, V=545.6(2) Å 3 , and Z=1 with R=0.0751 (all data). In 2, each dinuclear unit [Cu 2 (histamine) 2 (C 2 O 4 )] 2+ is coordinated with a nitrate anion and a water molecule, and they are held together by the hydrogen bonding interactions to form a ladder-like chain. The magnetic susceptibility data of 1 and 2 measured in 2–300 K provide the magnetic parameters, g=2.08, J=−166 cm −1 , J′=6.46 cm −1 , ρ=0.0026, Nα=155×10 −6 cm 3 mol −1 , and R=1.03×10 −3 (g=2.05, J=−162 cm −1 , J′=10.5 cm −1 , ρ=0.0029, and R=2.95×10 −3 with the fixed value of Nα=120×10 −6 cm 3 mol −1 ) for 1 and g=2.00, J=−158 cm −1 , J′=26.5 cm −1 , ρ=0.0020, Nα=136×10 −6 cm 3 mol −1 , and R=7.31×10 −4 (g=2.01, J=−157 cm −1 , J′=25.0 cm −1 , ρ=0.0021, and R=1.32×10 −3 with the fixed value of Nα=120×10 −6 cm 3 mol −1 ) for 2. These indicate that very strong antiferromagnetic interactions occur along the rungs of the ladder via the oxalate bridge and weak ferromagnetic interactions along the chains.