This paper presents a comparative study of catalytic activity of 12 different styrene-divinylbenzene ion-exchange resins as catalysts for MTBE (methyl tert-butyl ether) liquid-phase synthesis. Experiments were carried out at 1.6 MPa and 323 K using a stationary fixed-bed fed with methanol and C-4 olefinic cut as the source of isobutylene. The isobutylene/methanol molar ratio studied was 0.91 and the LHSV employed in the continuous operation was 85 h(-1). Experimental data show that ion exchangers with higher acidic capacity were the most active ones. It seems that this parameter plays the greatest influence on the catalytic activity for MTBE synthesis whereas other properties such as surface area and average pore diameter hardly influence it.