The addition of 1 eq of HCI (relative to available chloride) to a 49:51 AlCl3:ImCl (lm+ = 1-ethyl-3-methyl-1H-imidazolium)ionic liquid results in expansion of the electrochemical window of the melt to that more characteristic of a Lewis neutral melt. This is owing to the activity of H2Cl3- or HAlCl5- which, being weak Lewis acids in nature, serve to maintain a low chloride ion concentration. Voltammetric results suggest that several electroactive protic species are present.