Conjunct polymers, which are byproducts formed during the alkylation of isobutane with C3-C5 olefins, dilute the acid catalyst used so that it eventually loses effectiveness. For alkylations involving both n-butenes and sulfuric acid, decomposition of sec-butyl sulfates produces conjunct polymers, liquid hydrocarbons rich in heavy isoparaffins and olefins, sulfur dioxide, and water. During alkylation the polymers are present as conjunct polymer sulfates that contain sulfone, sulfonic acid, or sulfonic acid ester groups. NMR and IR spectroscopies were used to elucidate the structure of the conjunct