The invention provides a working electrode for use in an undivided electrochemical cell that is composed of at least one three dimensional accordion pleated sheet member having an open surface area of from zero to 50%. Typically suitable materials include metal mesh and woven fibers. The invention also includes an undivided electrochemical cell, containing the novel working electrode. Finally, the invention includes a method for electrochemically treating a metals-containing hydrocarbon stream in an undivided electrochemical cell by contacting a metals containing hydrocarbon stream with the novel pleated electrode. The invention has broad applicability for treating starting materials that produce electrochemically reversible (redox active) intermediates.