Nanostructures of Fe oxides and hydroxides with varying morphologies have been prepared in aqueous media by precipitation of iron nitrate and ammonium hydroxide. The approach is based on a simple wet-chemical route involving different solutions of Fe-oxide/hydroxide particles in suspension and acetic acid at different concentrations and subject to heat treatment at 373 K. The growth and structural characteristics have been investigated using x-ray diffraction (XRD) and high-resolution scanning electron microscopy (HRSEM). XRD results indicate that the solids obtained from aqueous stage exhibit goethite [alpha-FeO(OH)] with average particle size of 2-3 nm, while the samples with acetic acid addition show hematite (alpha-Fe2O3) with average size of similar to 20 nm. HRSEM results confirm the presence of particles of similar to 100 nm in samples with no acetic acid, while the samples with acetic acid exhibit nanoparticles of similar to 20 nm. The analysis also indicates the presence of net-shaped structures and particles with high-dense porosity within the nanoregime depending on the concentration of acetic acid. Fe-oxide nanoparticles and networks are stable up to a temperature of 773 K. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3336680]