In this work, a simple and versatile strategy to synthesize water dispersible high quality nanocrystals was reported. To demonstrate this strategy, thermolysis synthesis of magnetite nanocrystals was coupled with a classical maleinization reaction. The resulting nanocrystals were protected with hydrophobic oleic acid ligands bearing the succinic anhydride functional group. Through a simple anhydride ring opening process, the ligand could be readily converted into its hydrophilic analogue and therefore the nanocrystals were dispersible in aqueous phase. The TEM, XRD and VSM results revealed that the size, shape monodispersity and the physical properties of the obtained hydrophilic nanocrystals did not differ considerably from the hydrophobic nanocrystals obtained from a typical thermolysis process. The cell cytotoxicity tests with NIH/3T3 revealed the biocompatibility of such hydrophilic functional capping agents of magnetite nanocrystals even at a high concentration (15.84 mM Fe). Lastly, our preliminary results with up-converting nanocrystals showed that this strategy was readily extendable to other nanocrystalline systems.