The voltammetric and chronoamperometric electro-oxidations of 2-propanol and acetone were carried out in base over Pt, Pt–Ru, and Ru nanoparticle electro-catalysts. A low-potential current maximum occurs during chronoamperometric electro-oxidations attributed to a reversible 2-propanol/acetone redox couple. The potential of this current maximum becomes more negative with increasing Ru content.