Water dispersible magnetite nanoparticles (Fe3O4) were synthesized by thermal decomposition of iron (III) acetylacetonate (Fe(acac)(3)) in the presence of carboxylic acid-terminated poly(ethylene glycol) (mPEG acid), poly(vinyl alcohol) and NH2-containing polyether. Crystal structure was investigated using X-ray diffractometry (XRD) and it showed that the as-synthesized particles had high crystallinity with distinct lattices. Particle size of the nanoparticles was investigated using XRD (15.32 nm), transmission electron microscopy (18.8 nm) and photo correlation spectroscopy (32 nm) techniques. Vibrating sample magnetometry indicated that magnetite nanoparticles exhibited superparamagnetic behavior at room temperature. Influence of each functional group on magnetic properties of the particles was also examined. These magnetite nanoparticles remained dispersible in aqueous dispersions with only 5% particles aggregating after 1 month of preparing.