Alkylation processes are described. The processes utilize ionic liquid catalysts having a kinematic viscosity range of about 50 cSt to about 100 cSt at 25° C. Catalysts within this range produce alkylate having higher octane than catalysts outside this range, especially at higher process temperatures which are preferable from an operating cost standpoint. The alkylate can have one or more of a research octane number of at least about 93, a selectivity of C8 of at least about 65%, and a mole ratio of trimethylpentane to dimethylhexane of greater than about 7:1.