In this study, a hydrophobic and thermostable amine-modified graphene oxide (MGO) material was fabricated using two different methods. p-Toluidine was covalently introduced onto the surface of graphene oxide (GO) sheets using direct and indirect amidation processes to obtain the amine-modified GO (MGO-1 and MGO-2). Successful grafting of p-toluidine at the graphitic framework of graphene oxide was confirmed using infrared spectroscopy and ultraviolet-visible spectroscopy. X-ray photoelectron spectroscopy showed the simultaneous reduction and modification. The reduced weight loss, increased initial decomposition temperature and enhanced residue formation indicate significant improvement of the thermal stability of MGO compared to GO. In addition, MGO-2 has greater thermostability and hydrophobic properties than MGO-1, with a water/air contact angle of ∼126.4°. The hydrophobic and thermostable MGO material could be applied to separate organic contaminants from water, which has great potential in environmentally friendly, low-cost advanced liquid–liquid separation or water treatment technologies.