Inorganic-organic hybrid materials with controllable electrical and magnetic properties can be obtained by combining inorganic magnetic constituents with conducting polymeric materials [1, 2]. These materials can effectively shield electromagnetic waves generated by electric and magnetic sources. Manganese ferrite (MnFe2O4) exhibits remarkable magnetic properties, extensively used in various technological applications such as recording media devices, drug delivery, ferrofluid, biosensors, and contrast-enhancement agents for MRI technology. On the other hand, polyaniline (PANI) is a conducting polymer with high electrical conductivity, excellent environmental stability, very light weight, flexibility and facile processability. Due to its excellent properties, PANI is widely used for many applications such as electromagnetic interference (EMI) shielding, sensors, diodes, light weight batteries, microwave absorption, corrosion inhibitors [2,3], etc. In the current study, magnetic MnFe2O4 nanopowders were prepared by an original, simple solvothermal method and MnFe2O4/ PANI hybrid materials were synthesized by in situ polymerization of aniline in the presence of MnFe2O4 nanopowders. MnFe2O4 was prepared using Mn(II) and Fe(III) chlorides as precursors, triethylene glycol as solvent, potassium hydroxide as precipitant and different surfactants such as tetra-nbutylammonium bromide and Tween 80. MnFe2O4/ PANI hybrid materials were prepared by polymerization of aniline on the surface of MnFe2O4 using ammonium persulfate as oxidant. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermal analysis (DSC-TG), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), specific surface area, particle size, pore size distributions, electrical and magnetic properties. The properties of MnFe2O4/ PANI hybrid materials were compared with that of MnFe2O4 and of PANI.