Solar photocatalytic degradation of phenol was performed using TiO 2 films deposited inside glass tubing by a spray-gel technique. Photocatalytic phenol degradation experiments were performed using either solar radiation or a 300 W lamp simulating the UVA solar radiation component. In order to concentrate the radiation a reflective surface was placed in the rear part of the tube. The obtained TiO2 films were amorphous, but after annealing at 450°C for 1 h, the films crystallized to the anatase structure and presented photocatalytic activity. The films' morphology, observed by scanning electron microscopy, presented a uniform film and agglomerates of TiO2. The size of the agglomerates increases as Ti isopropoxide/ethanol molar ratio of the starting solution increases. The concentration of the precursor solution and the film thickness of TiO 2 was optimized for phenol degradation. The TiO2 film obtained with a Ti-isopropoxide/ethanol molar ratio of 0.0259 and a film thickness between 1.2 to 2.4 μm were shown to yield the highest phenol degradation. Copyright © 2007 by ASME.