Another embodiment of the invention is a process for making at least one isooctane comprising: (a) obtaining a fermentation broth comprising isobutanol; (b) separating dry isobutanol from said fermentation broth to form separated dry isobutanol; (c) contacting the separated dry isobutanol of step (b), optionally in the presence of a solvent, with at least one acid catalyst at a temperature of abou