In this piece of work, high quality and homogeneity, barium hexaferrite (BaM) BaFe12O19 nanoparticles were prepared from organometallic precursors for the 1st time. This method is based on the formation of supramolecular crystal structure of Ba[Fe(H3NCH2CH2NH3)]Cl-7 center dot 8H(2)O. The crystal structure, morphology and magnetic properties of BaFe12O19 at two different annealing temperatures namely 1000 degrees C and 1200 degrees C were investigated using X-ray diffraction, transmission electron microscope TEM and vibrating sample magnetometry (VSM). The results show that monophasic nanoparticles of hexaferrites were obtained. Nanoparticles of crystallite size 40-50 nm distinguished by narrow distribution and excellent homogeneity were obtained with superior magnetic properties which suggested single-domain particles of Ba-M hexaferrite. (C) 2013 Elsevier Ltd. All rights reserved.