The objective of materials research is the development of economical, safe and efficient synthesis routes that lead to the formation of a photocatalyst which is able to overcome performance problems related to particle size, crystallinity, or low surface area. Here, we report high-quality functional nanoparticles of calcium bismuth mixed oxide with 15 nm nominal size corresponding to a specific surface area of 41 m(2)/g which were produced by single-step flame spray synthesis (FSS). The high temperature of the flame afforded creation of oxygen vacancies which were quantified by near edge X-ray absorption fine structure (NEXAFS) spectra. These two parameters, developed active surface area and created in the flame oxygen vacancies, allowed to enhance the photocatalytic activity of calcium bismuth oxide by a factor of 6, in comparison to previously reported calcium bismuth mixed oxide produced by conventional methods which required additional temperature treatment steps. (c) 2010 Elsevier B.V. All rights reserved.