The development of sunlight-activated and environmentally friendly photo-catalysts for wastewater treatment and air purification is an open scientific and technological challenge. In this regard, the present work reports on a Chemical Vapor Deposition route to phase-pure iron(III) oxide nanosystems [alpha-Fe2O3 (hematite) and beta-Fe2O3 (bixbyite)]. The obtained polymorphs have been characterized in detail in their nanostructure, composition, morphology and optical properties. The synthesized supported Fe2O3 nanomaterials have also been tested in the photo-degradation of a model organic dye (methylene blue) in the liquid phase, as well as in the photooxidation of NO in air, both activated by simulated solar light. The obtained results, of interest for eventual use in water and air purification, are critically discussed as a function of nanosystem chemico-physical properties. (C) 2014 Elsevier B.V. All rights reserved.