Mercury in aqueous streams poses severe health and environmental concerns and requires improved techniques for decontamination. One such technique is electrochemical alloy formation on platinum, which can effectively decontaminate mercury-containing aqueous streams at concentrations relevant for both industrial and natural waters. This study examines the viability of copper as an alternative to platinum. Mercury removal is faster on copper and works both with and without an applied cathodic potential. Without it, however, copper dissolution becomes a problem. Copper dissolution is preventable in neutral pH and in sulfuric acid solutions under potential control, and dissolved copper ions can be plated back onto the electrode. In the presence of nitrate or chloride anions, copper electrodes degrade rapidly even under potential control. Thus, there are practical restrictions for mercury decontamination via electrochemical alloy formation on copper, but it can be applied to solutions where copper is stable under potential control.