The oxygen electrode plays a crucial role in performance and lifetime of water electrolyzers and regenerative fuel cells due to its slow electrochemical processes under rigorously oxidizing or reducing environments. Herein, we report the use of titanium carbonitride as an efficient and stable support in acidic media. Pt3M (M = Ru, Ir, Ta) nanoparticles supported on titanium carbonitride were synthesized by the ethylene glycol method and characterized by transmission electron microscopy, X-ray diffraction and inductively coupled plasma optical emission spectrometry. The electrochemical activity toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), as well as the stability of the catalysts, was tested employing a rotating ring-disk electrode. The activity of the three catalysts is similar for the ORR. However, for the OER, Pt3Ru/TiCN appears to be the best catalyst by far. Pt3Ru/TiCN was also compared with a commercial RuO2 catalyst, obtaining a better performance for the supported catalyst even though the low amount of Ru/RuO2 present in the supported sample. The high activity and stability of the Pt3Ru/TiCN catalyst for the ORR and OER is due to an interesting promotion effect of the titanium carbonitride support, so that this electrocatalyst has a great potential for the application in unitized regenerative fuel cells. (C) 2015 Elsevier B.V. All rights reserved.