The simultaneous adsorption of a sulfur compound [dibenzothiophene (DBT)] and a nitrogenous compound [quinoline (QN)] was studied on nickel-loaded granular activated carbon (Ni-GAC). Taguchi's L-27 methodology was used to investigate the effect of various operating parameters and optimize them. Parameters studied during simultaneous adsorption included the initial DBT/QN concentration (C-o,C-i), Ni-GAC dose, temperature, and contact time. The Ni-GAC dose was found to be the most significant factor, while the interaction between Co values was also significant. Optimized parameters of Taguchi experiment were further used for determining binary isotherm behavior. The adsorption capacity of Ni-GAC for QN adsorption was found to be greater than that for DBT. Among various multi-component empirical models, the extended Freundlich model best followed the binary isotherm experimental data at 303 K. DBT and QN adsorption data were also analyzed and represented by models based on ideal and real adsorbed solution theories.