The effect of the acid-hydrocarbon ratio and temperature on the isobutane-isobutylene alkylation with trifluoromethanesulfonic acid was studied over the temperature range of 40 degrees C greater than or equal to T greater than or equal to 80 degrees C. The effect of acid/hydrocarbon ratios and temperature passes through a maximum giving high quality alkylate of approximately 70% branched C-8 products at -30 degrees C, with a catalyst/hydrocarbon ratio of 0.5. The optimum reaction conditions also depend on the induction period and the effect of secondary reactions influenced by contact time. TFSA is a readily recyclable acid without the need for any purification or regeneration.