The non-ideal adsorbed solution (NAS) theory was here applied to the correlation of non-ideal binary gas adsorption equilibria of volatile organic compounds (VOCs) on activated carbon BPL. Pure adsorption isotherms for methanol, acetone, benzene, n-hexane, and toluene were measured at three temperatures (293, 323, 353 K) over a range of relative pressures (2 x 10(-7)-1 x 10(-2)) on activated carbon BPL. Binary gas adsorption equilibria on BPL for toluene/benzene, benzene/acetone. and n-hexane/acetone were measured using both head-space gas chromatography (HSGC) and dynamic methods. Calculations based oil the ideal adsorbed solution (IAS) theory correlated well only with the results for the toluene/benzene system, which is considered an ideal mixture. However, the NAS provided much more accurate correlation for non-ideal systems (benzene/acetone and n-hexane/acetone). Furthermore, the NAS was capable of predicting the azeotropic behavior of a highly non-ideal system (toluene/1-propanol On Y-zeolite, from the literature). We concluded that NAS was a useful predictor of non-ideal binary gas adsorption equilibria of VOCs.