The photocatalytic mineralization of oxalic acid over SiO2-based materials was investigated in the 200-800 nm range. The photocatalytic activity was found to be strongly related to the morphology of SiO2 materials. The simple as well as the Pt-modified SiO2 particles having a predominant spherical shape exhibited null photocatalytic activity. In contrast, the tubular shaped SiO2 particles revealed an interesting photocatalytic activity, the rate of CO2 evolvement being 45 A mu mol g (cat) (-1) h(-1). The initial activity was significantly enhanced (428 A mu mol CO2 g (cat) (-1) h(-1)) by platinum photodeposition on the outer and inner surface of tubular SiO2. The catalytic materials were characterized by TEM, UV-VIS and XPS to obtain rational explanations for the phocatalytic activity that was noticed. The experiments revealed that SiO2 tubes behave as efficient photooxidation microreactors. The morphology-dependent photocatalysis can be an efficient tool in future for the abatement of pollutants in liquid phase.