Photocatalytic inactivation of Bacillus anthracis was studied by using titania nanomaterials and UVA light. Experimental data clearly indicated that, time of exposure, quantity of catalyst, intensity of light, particle size and Sunlight affected the inactivation. It also demonstrated the pseudo-first order behavior of inactivation kinetics and pointed out the enhanced rate of inactivation in the presence of nano-titania existing as a mixture of anatase and rutile phases. The values of rate constant were found to increase when the quantity of catalyst and intensity of UVA light were increased. Nanosized titania exhibited better inactivation properties than the bulk sized titania materials. Sunlight in the presence of nano-titania (mixture of anatase and rutile phases) displayed better photocatalytic bactericidal activity of B. anthracis than sole treatment of Sunlight. (C) 2008 Published by Elsevier B.V.