Adsorption properties of sulfamethoxazole (SMX) as an antibiotic were promoted by graphene nanosheet (GNS) and Graphene oxide nanosheet (GOS). The five factors influencing the adsorption of SMX (initial SMX concentration, initial solution pH, amount of adsorbent, temperature and contact time) were studied. The results showed that adsorbent dosage of 0.010 mg, initial pH similar to 6 and contact time similar to 110 min are optimum for both systems. The monolayer adsorption capacity (q(m)) decreased with the increase of the temperature from 25 degrees C to 45 degrees C. Non-linear regressions were carried out in order to determine the best fit model for each system. To do this, 8 error functions were applied to predict the optimum model. Among various models, Redlich-Peterson and Koble-Corrigan isotherm models represented the equilibrium adsorption data of SMX while kinetic experimental data were well fitted by pseudo second-order model on both adsorbents. The study showed that GOS can be used as a more efficient adsorbent for the adsorption of SMX from water solution. (C) 2016 Published by Elsevier B.V. on behalf of The Institution of Chemical Engineers.