Activated carbons were prepared from carbonized PET by steam activation via pretreatment by mixing PET with a metal salt [Ca(NO3)(2).4H(2)O, Ca(OH)(2),CaCO3. ZnO, and AINH(4)(SO4)(2).12H(2)O], and with acid treatment after carbonization. The porous properties of the activated carbons were determined by the nitrogen adsorption method. The adsorption isotherms of CO2, C2H6, nC(4)H(10) and iC(4)H(10) at 298 K on the prepared activated carbons were measured to determine practical applications and to obtain a better understanding of the porous structure of the prepared carbons. Steam-activated carbons via pretreatment have a larger mesoporosity than carbons with no pretreatment. The metal salt used in the pretreatment for steam activation has no influence on the microporous structure. but it does influence the mesoporous structure of the prepared carbons. Activated carbons prepared via pretreatment show a large adsorption capacity for nC(4)H(10) and iC(4)H(10). These carbons are suitable as adsorbents for canisters, etc. Application of the potential theory to adsorption data for the prepared carbons suggests that the pretreatment contributes to the formation of pores larger than 0.50 nm at high burnoff. (C) 2002 Elsevier Science Ltd. All rights reserved.