Abstract: Porous SnO₂-Cu₂O composite films were prepared through thermal oxidation of porous Sn-Cu alloy electrodeposits in air.The effects of the Sn²⁺/Cu²⁺ molar ratio of solutions on the morphologies, constituents and structures of coupled SnO₂-Cu₂O porous films were investigated by scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy(EDS) and X-ray diffraction(XRD) analysis.And the photocatalytic activity of the films was tested by photodegradation of rhodamine B under irradiation of a low-pressure mercury lamp.The results indicate that a coupled SnO₂-Cu₂O porous film with a Sn∶Cu ratio of 3∶1 has the best photocatalytic activity for degradation of rhodamine B.The film was prepared by electrodepositing a Sn-Cu alloy in a solution containing 0.01 mol·L^-1 CuSO₄, 0.05 mol·L^-1 SnSO₄, 1.5 mol·L^-1 H₂SO₄, 7 mL·L^-1 formaldehyde and 0.001% polyethyleneglycol octyl phenyl ether(OP) at 6.0 A·cm^-2 and 20 ℃, then heating the Sn-Cu alloy at 200 ℃ for 2 h followed by 400 ℃ for 2 h in air.The reason for a higher photocatalytic activity of the film may be its three-dimensional porous morphology and proper Sn/Cu ratio.