The carboxylated graphene oxide (GO—COOH) was prepared by carboxylation of graphene oxide (GO) using succinic acid acyl peroxide. The product was characterized by means of infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetry, and the dispersion properties of GO and GO—COOH in water and toluene were observed. The results showed that the carboxyl terminal carboxyl groups generated by the thermal decomposition of succinic acyl peroxide were covalently grafted onto the GO surface. Compared with GO, GO—COOH had better dispersion stability in water, while the dispersion stability in toluene deteriorated, indicating that GO—COOH introduced more polar groups than GO. This method provided a new way for the GO surface to add more active sites.