BACKGROUND: Nano-sized titanium dioxide has potential as a photocatalyst, and doped variants may have different photocatalytic properties. Nano-titanias with a wide range of dopants and compositions can be prepared using continuous hydrothermal flow synthesis (CHFS), but when many samples are made, a large-scale screening test is required to investigate their properties. A range of doped nano-titanias were prepared using a CHFS route, and investigated as powders using a range of photocatalytic test methods. These tests included decolourization of methylene blue (in the presence of oxygen), partial oxidation of a simple alcohol (propan-2-ol) and the degradation of aqueous solutions of dichloroacetic acid. The practicality of the tests for large-scale screening was considered, and the test results were cross-correlated to see if any of them gave similar ranking for activity of the photocatalysts. RESULTS: Two of the tests, namely DCA degradation and propan-2-ol, gave similar rank ordering for the nanopowders, while the MB decolourization results did not suggest a strong correlation with any other test. The addition of metal dopants was observed to produce varying results between different dopants and tests. CONCLUSIONS: Two of the tests, DCA degradation and MB decolourization in visible light, were recommended for further use as screening tests. (C) 2009 Society of Chemical Industry