Studies on photocatalytic inactivation of spores of Bacillus anthracis have been carried out using nanosized titania materials and UVA light or sun light. Results demonstrated pseudo first order behaviour of spore inactivation kinetics. The value of kinetic rate constant increased from 0.4h-1 to 1.4h-1 indicating photocatalysis facilitated by addition of nanosized titania. Nanosized titania exhibited superior inactivation kinetics on par with large sized titania. The value of kinetic rate constant increased from 0.02h-1 to 0.26h-1 on reduction of size from 1000nm to 16nm depicting the enhanced rate of inactivation of Bacillus anthracis Sterne spores on the decrease of particle size. © 2010 Elsevier B.V.