Abstract A facile route for the functionalization in situ of graphene oxide with magnetite nanoparticles (Fe 3 O 4 @GO) was developed. We used graphene oxide with different oxidation time (12 and 24 hours) and each one was functionalized with different proportions of Fe 3 O 4 nanoparticles modifying the load of the iron precursor (FeSO 4 .7H 2 O). The as-synthesized materials were characterized by multiple spectroscopic techniques (FT-IR, Raman, DRX, XPS) to demonstrate the successful attachment of iron oxide nanoparticle on graphene oxide sheets. Transmission electron microscopy (TEM) revealed that magnetite NPs were firmly decorated on the surfaces of graphene oxides with the mean diameter of about 7 nm. The magnetometry studies showed ferromagnetic behaviour of all composites in the range of 44-66 emu/g at room temperature.