Graphical abstract A H 2 plasma, that aims at reducing the fraction of the oxidized species at the outermost perimeter of metal particles, has been used to treat the PtRu nanoparticles supported on the plasma functionalized multi-walled carbon nanotubes (PtRu/PS-MWCNTs). The plasma treated PtRu/PS-MWCNTs exhibit increased electrochemically active surface area, reduced charge transfer resistance, improved electrocatalytic activity and long term stability toward methanol and formic acid oxidation, and enhanced tolerance to carbonaceous species relative to the sample untreated with the H 2 plasma. Highlights ► A H 2 plasma technique is used to treat the PtRu nanoparticles. ► The H 2 plasma treated PtRu/PS-MWCNTs exhibit improved electrocatalytic activity. ► The H 2 plasma treated PtRu/PS-MWCNTs have significantly reduced charge transfer resistance. ► The H 2 plasma treated PtRu/PS-MWCNTs show the increased stability. ► The Pt:Ru atomic ratio of PtRu nanoparticles has a significant effect on the electrochemical activity.