Large surface area coatings of oxygen deficient nanocrystalline TiO2 are of immense use in antifogging mirrors and self cleaning windows. Spray pyrolysis is a simple versatile technique to coat relatively large surface area. A clear understanding of effect of substrate temperature on the coating morphology, structure, composition and optical properties is essential to produce coatings of desired properties. Oxygen deficient nanocrystalline anatase-TiO2 thin films were synthesized on Si(1 00), quartz and glass substrates at 300-550 degrees C. Well defined platelets like nanograins standing on their edge were obtained at 500 degrees C. The crystallites were found to be of similar to 12 nm thickness and similar to 30 nm major diameter. The secondary ion mass spectrometric studies of the films revealed uniform distribution of titanium and oxygen across the thickness of the film up to the film-substrate interface. Presence of lower valent Ti ions and oxygen vacancies were confirmed from XPS studies. The indirect and direct band gap values evaluated from the Tauc plot for films synthesized at 500 degrees C are 3.3 and 3.62 eV respectively. (C) 2011 Elsevier Ltd. All rights reserved.