The ability of titania to photo-catalytically destroy organic pollutants has led to its use in many applications including anti-biological and self-cleaning materials. Various methods have been used to improve the efficiency of the photocatalytic process, including modifications to the sample morphology by improved crystallinity or increasing surface roughness and hence increasing the surface area and the efficiency in which the pollutant can be exposed to the active TiO2. However, this latter has to be balanced by the commercially driven need for transparent and hence thin films (< 40 nm), as generally the roughness (and photo-activity) increases with increased thickness of the deposited layer. In this paper we discuss the growth and characterisation of atmospheric pressure CVD grown colourless, transparent thin films. We propose, in particular, to show how the photocatalytic behaviour is affected by growth parameters and discuss this in relationship to factors such as morphology, roughness and crystallinity.