Nanoshell hollow iron oxide (alpha-Fe2O3) spheres and nanoparticles were produced by ultrasonic spray pyrolysis (USP) method from iron(III) chloride salts. Iron oxide nanostructures were obtained by thermal decomposition of aerosol formed in the ultrasonic generator from aqueous solution of FeCl3 as a precursor. Hollow structure of iron oxide particles was controlled by reaction temperature changing between 600 and 200 degrees C and with the addition of the polyethylene glycol (PEG) iron oxide nanoparticles were fabricated. X-ray diffraction (XRD) studies and Scherrer crystalline size calculations show that the crystal sizes of the nanostructured iron oxide were between 33 and 18 nm. Energy dispersive spectroscopy (EDS) was performed to determine the chemical composition of the particles. Scanning electron microscope (SEM) investigation gave detailed information about particle size and morphology. Transmission electron microscope (TEM) was used to confirm the hollow structure of the particles and identify the thickness of the shell. (c) 2009 Elsevier B.V. All rights reserved.