Abstract: A water based double surfacted ferrofluid having magnetite nanoparticles (2-18 nm) coated with primary and secondary surfactants is synthesized. On the other hand, an aqueous dispersion of functionalized MWCNT (diameter=14-18 ?m, length=1.6-2.5 ?m) is prepared by acid treatment. A hybrid solutions in different v/v ratios yielded stable dispersions having both nanoparticles and nanotubes in itself behave as one system. The synthesized hybrid fluid show magnetic response and self-sustained homogeneity of in presence of magnetic field. In addition, the hybrid fluids exhibits a long term sedimentation and magnetic stability which enables one to use them for various applications like MRI, EMI shielding, energy conversion etc.