Abstract: An alkylation catalyst can include: a Brønsted acid ionic liquid; and a strong Brønsted acid that is not considered an ionic liquid. The Brønsted acid ionic liquid can be selected from the group consisting of [BMIm]HSO4, [MBSIm]HSO4, [MBSIm]OTf, [MPSIm]OTf, and [OMIm]HSO4 or the like. In one aspect, the strong Brønsted acid is selected from the group consisting of sulfuric acid, hydrochloric acid (HCl), hydrobromic acid (HBr), HF, hydrogen iodide (HI), phosphoric acid, trifluoromethanesulfonic (triflic) acid. In one aspect, the strong Brønsted acid is present at more than about 50 wt % of the composition; however, the Brønsted acid can vary from about 10 wt % to about 99 wt %, more preferably about 20 wt % to about 90 wt %, and most preferably about 40 wt % to about 80 wt %.