ABSTRACT.The introduction of electrode placement caps as a rapid means of electrode application has prompted an evaluation of their position placement accuracy and technical reliability for electroencephalography (1). Such caps appear to provide quick, highly consistent electrode placement, ready adaptation for unconventional electrode sites (e.g.“Oz”) and reliable recordings for EEG activity. However, it is not clear how the tin electrodes employed in these devices might affect event-related potential (ERP) recordings. Since metals differ in their capability to transmit electrical signals (2) and because a long time-constant is optimal for recording of several ERP components (3) a comparison of ERPs recorded with the often used nonpolarizable silver/silver chloride (Ag/AgCl) electrodes and the tin electrodes was made.