Electroreduction of oxygen in alkaline solution on glassy carbon (GC) electrodes modified with different carbon nanomaterials has been studied. Electrochemical experiments were carried out in 0.1 M KOH employing the rotating disk electrode and rotating ring-disk electrode methods. The GC disk electrodes were modified with carbon nanomaterials using polytetrafluoroethylene as a binder. Four different carbon nanomaterials were used: multiwalled carbon nanotubes, carbon black powder, and two carbide-derived carbons (CDC). For the first time, the electrocatalytic behavior of CDC materials toward oxygen reduction is explored. Electrochemical characterization of the materials showed that all the carbon nanomaterial-modified GC electrodes are highly active for the reduction of oxygen in alkaline solutions.