BACKGROUND: The authors (Chem Eng J 148, 234 (2009)) previously demonstrated the excellent performance of a photocatalytic reactor with a parallel array of nine light sources. To enhance the possibility of practical application of this reactor, the present work explores the use of a PET (polyethylene terephthalate) sheet as a new cheap material to support TiO(2), as an alternative to glass tubes. A method of coating the hydrophobic PET sheet with a TiO(2) film using an aqueous coating solution is investigated and the performance of the TiO(2)-PET sheet prepared evaluated. RESULTS: The affinity of the coating solution for the PET sheet is greatly enhanced by addition of 0.01% (w/w) nonionic surfactant (polyoxyethylene lauryl ether). A relatively uniform thin TiO(2) film is formed on the entire surface of the PET sheet by applying the coating solution to the PET sheet and drying it at 100 degrees C. Decomposition experiments of gaseous HCHO indicate that the photocatalytic activity, although initially low, is increased with repeated use. This is because surfactant molecules added interfere initially with the decomposition of HCHO. After their decomposition, the TiO(2)-PET sheet decomposes HCHO at almost the same rate as does the TiO(2)-glass tube. CONCLUSION: The photocatalytic reactor with a parallel array of nine light sources can utilize a PET sheet as TiO(2) support with a reduction in material cost. (C) 2011 Society of Chemical Industry