A functionalized multiwall carbon nanotube (MWCNT)-COOH/Fe3O4 hybrid was fabricated by co-precipitation method. Fe3O4 nanoparticles were stably attached to the surface of carboxyl groups (COOH). The presence of Fe3O4 nanoparticles and their surface conjugation to MWCNT have been confirmed by XRD, TEM and FT-IR techniques. Magnetic evaluation revealed a superparamagnetic character of the hybrid and therefore the attached Fe3O4 nanoparticles. The crystallite size (9 +/- A 3 nm), particle size (9 +/- A 2 nm) and magnetic domain size estimated for Fe3O4 are consistent with each other, which reveal the single crystalline character of the nanoparticles. Electrical conductivity and dielectric behavior have also been characterized by utilizing impedance spectroscopy up to 3 MHz for an isotherm line varying from 293 to 393 K by 10 K steps. Electrical characteristics and its complex dielectric approaches might be elucidated with the existence of a conventional tunneling conduction mechanism of temperature-independency. The AC conductivity of MWCNT-COOH/Fe3O4 hybrid could also be a consequence of the estimations of the universal dynamic response.