The photodegradation of acetylene (C2H2) was investigated over various powders or supported titanium dioxide (TiO2) photocatalysts in air into static conditions. It was found that UV-irradiated TiO2 is effective in order to lead to the complete mineralization of the pollutant containing a triple carbon-carbon bonding without deactivating. No organic intermediates were detected in the gas phase, implying that oxidation mechanisms take place in the adsorbed phase. The efficiency of P25-Degussa and PC500-Millennium photocatalysts were compared; the mixed anatase/rutile P25-Degussa is reported as the most efficient photocatalytical material in our conditions. The topology of the photocatalyst support is reported as a significant parameter in TiO2 efficiency. Fibre-deposited photocatalysts lead to the highest activity, and the chemical nature of the fibre did not influence the photodegradation. The influence of TiO2 amonut, silica binder and adsorbing additives such as zeolite, and activated carbon coupled with TiO2 photocatalyst were investigated. (c) 2005 Elsevier B.V. All rights reserved.