To obtain the surface content of Ru is rough electrocodeposited PtRu electrodes, the mass change of a Pt electrode during Ru deposition was measured with the electrochemical quartz crystal microbalance (EQCMB). It is shown that there is a correlation between the potential of the surface oxide reduction peak of the PtRu electrode and the surface Ru content. With the EQCMB also the methanol oxidation and oxide formation on both Pt and PtRu were studied. Implications for the oxidation of CO and CH3OH are discussed, in the context of which some IR experiments on CO and PtRu are presented as well.