Polyaniline/BaFe12O19 composites synthesised by two different polymerization pathways: chemical polymerization and solid-state polymerization, were studied. The influence was explored by the type of polymerization synthesis on the microstructure and on the magnetic properties of the composites. Structural, morphological and magnetic properties of the nanocomposites were performed by XRD, FTIR, SEM and VSM measurements, respectively. XRD analysis revealed the inorganic phase as barium hexaferrite and FTIR analysis indicated an interaction between hexaferrite particles with Polyaniline regardless the synthesis method. The powder morphologies obtained from SEM revealed very similar particle sizes for the two routes while the extent of agglomeration was higher for the chemical polymerization method. Polyaniline/ BaFe12O19 composites exhibited a ferromagnetic behaviour. The powders obtained by solid-state polymerization presnted better magnetic characteristics (for 70% Polyaniline/BaFe12O19 composite, saturation magnetization 25.37 Am²/Kg) than those obtained by chemical polymerization.