A comparative study of physicochemical and magnetic properties of Polyaniline-BaFe12O19 composites prepared by Solid-Based Polymerization (SBP) and by Aqueous-Based Polymerization (ABP) is carried out. The composites obtained by the latter method underwent a grinding to study the influence of shear stress. Thus, in a systematic approach, an investigation of stirring effect was done by synthesizing these composites using aqueous-based polymerization but without mechanical stirring. Different mass ratio of BaFe12O19 was used to explore their impact on composites properties. X-ray diffraction, FTIR, SEM, TGA, conductivity and vibrating sample magnetometer measurements were performed. Structural and morphological investigations confirmed the presence of polyaniline and barium hexaferrite phase, which were in interaction in the composites regardless the polymerization route. The powder obtained by solid-based pathway revealed distinct particles with uniform distribution for various compositions (wt. %) of BaFe12O19 in Pani, while the composites obtained by aqueous-based polymerization presented agglomerated nanostructures. Thermogravimetric analysis exhibited an improved thermal stability for Pani-BaFe12O19 obtained by solid-based route. The electric conductivity has displayed decreasing trend of DC conductivity with the increase of BaFe12O19 particles in the polymer matrix. Magnetic studies showed a ferromagnetic behaviour for all composites. The saturation magnetization monotonously increased with the increasing of BaFe12O19 amount. The magnetic properties of the powders were mainly related to the hexaferrite loading which was determined using measured magnetic data. These results revealed that magnetization saturation was dependant of volume fraction of ferrite in the composites which was significantly affected by the reaction medium and mechanical stirring. The powders obtained by solid based polymerization manifested enhanced magnetic characteristics. The solventless reaction medium contributed to the increase of volume fraction of ferrite in the composite compared to the aqueous reaction medium. Moreover, the mechanical stirring during aqueous-based polymerization had an important influence on the volume fraction of ferrite since. it prevented the dissolution of BaFe12O19 particles. (C) 2016 Elsevier B.V. All rights reserved.