Abstract: A powdery photocatalyst based on titanium dioxide displays a bimodal particle size distribution of primary particles, with one particle component under about 30 nm and a second particle component over about 100 nm. The photocatalyst is manufactured by mixing at least two TiO2 components. One component is a TiO2 photocatalyst which is active in UV light and/or in visible light and which displays a specific surface according to BET of at least about 120 m2/g. The second component is anatase and/or rutile displaying a specific surface according to BET of less than about 50 m2/g. The two components are contained in the photocatalyst at a weight ratio of 1:1000 to 1000:1.