Liquid phase adsorption (298 K, batch technique) of linear and branched paraffins (tetradecane, 3-methylpentane, 2,3-dimethylpentane and 2,2,4-trimethylpentane) has been studied onto several microporous adsorbents with different structures and Si/Al molar ratios: H-Beta (BEA), H-ZSM-5 and S-1 (MFI) and SAPO-11 (AEL). MFI samples showed no adsorption of the geminal paraffin due to molecular sieve effect, as well as a preferential adsorption of the linear paraffin. A competitive adsorption between the mono- and dibranched paraffins was observed onto MFI samples, showing an increase in adsorption capacity for 3-methylpentane at higher Si/Al molar ratios. AEL and BEA samples adsorbed significant amounts of all adsorptives. A mixture Of C-13 isomers containing different amounts of tridecane, monomethyldodecanes, dimethylundecanes, trimethyldecanes, ethylundecanes and other polimethyl paraffins was also tested onto commercial H-ZSM-5, pure (Si/Al=13, 16, 54) and agglomerated (Si/Al=24, 45, 200), as well as onto two commercial pure silicalites. Only dimethyl, monomethyl and linear paraffins were significantly adsorbed. Adsorption capacities of the five monomethyl isomers increased following the sequence 6M-C-12>5M-C-12>4M-C-13>3M-C-12>2M-C-12, specially at low Si/Al molar ratios. (C) 2006 Elsevier B.V. All rights reserved.