For the synthesis of Fe 3 O 4 @Tween20 nanocomposite, two surfactants (Tween20 and oleic acid) were used to overcome the aggregation. The nanoparticles were used to prepare a water-based Fe 3 O 4 @Tween20 nanocomposite using oleic acid and Tween20 as surfactants ( Fe 3 O 4 colloidal superparticles were developed by introducing Tween20 as a surface modification agent to maintain the colloidal stability of the F e 3 O 4 superparamagnetic nanoparticles (SPION)). Vaseline and the synthesized iron oleate were used for the polyol synthesis of Fe 3 O 4 @Tween20 nanocomposite. The product has superparamagnetic property. Fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric analysis (TGA) proved the presence of both surfactants on the surface of the Fe 3 O 4 nanoparticles. The product may have potential use in magnetic resonance imaging and hyperthermia.