This study shows two sizes of graphene oxide nanoparticles (GO–450 nm and GO–200 nm) which are introduced as adsorbents to remove Bromophenol blue dye. The GO–450 nm was made by oxidation-reduction reaction, followed by tip sonication to obtain GO–200 nm. The microscopic and spectroscopic properties were realised using scanning electron microscopy and FTIR spectroscopy, respectively. The batch adsorption was used to evaluate the removal of BPB onto both sizes of adsorbents. The amount of BPB that was successfully removed depending on the pH, the adsorbent dose, the contact time, the initial dye concentration, and the reaction temperature. The optimal conditions for the removal of BPB were at pH = 2, applying a dose of 160 mg/ml and for a contact time of 40 minutes. Moreover, the experimental data agree well with the Langmuir isotherm in both cases, and the maximum adsorption capacities of removal of BPB dye were found to be 28.57 mg/g and 40 mg/g for GO–450 nm and GO–200 nm, respectively. The percent removal of BPB dye was enhanced in the presence of NaCl ionic strength. The thermodynamic parameters like ∆G, ∆H and ∆S were elucidated.