Aluminosilicate nanotubes and Cu(II)-grafted TiO2 composites were prepared, and the acetaldehyde degradation activity of the composites was evaluated at various relative humidities. The aluminosilicate nanotubes were synthesized hydrothermally and characterized by TEM, XRD, Al-27 and Si-29 NMR, FT-IR, N-2 and water vapor isotherms. Their morphology was nanotubular with 3-5 nm outer diameter, and the specific surface area was 245 m(2)/g. The aluminosilicate had a strong affinity for water molecules, and the structure was determined to be an imogolite by (27)AI and Si-29 NMR. TiO2 and imogolite composites exhibited higher activity for the photodegradation of acetaldehyde under UV irradiation than TiO2, but was dependent on the relative humidity. Cu(II)-grafted TiO2 and imogolite composites exhibited higher activity for the photodegradation of acetaldehyde under visible light irradiation than Cu(II)-grafted TiO2, and were less affected by the relative humidity. These results show that Cu(II)-grafted TiO2 - imogolite composites exhibit very efficient absorption and photodecomposition of acetaldehyde in a variety of environments. (C) 2013 Elsevier B.V. All rights reserved.