A process for determining ionic liquid catalyst deactivation including (a) collecting at least one sample of an ionic liquid catalyst; (b) hydrolyzing the at least one sample to provide at least one hydrolyzed sample; (c) titrating the at least one hydrolyzed sample with a basic reagent to determine a volume of the basic reagent necessary to neutralize a Lewis acid species of the ionic liquid catalyst; and (d) calculating the acid content of the at least one sample from the volume of basic reagent determined in step (c) is described. Processes incorporating such a process for determining ionic liquid catalyst deactivation are also described. These processes are an alkylation process, a process for controlling ionic liquid catalyst activity in a reaction producing by-product conjunct polymers, and a continuous process for maintaining the acid content of an ionic liquid catalyst at a target acid content in a reaction producing by-product conjunct polymers.