Six specimens of ultrafine RuO2-IrO2-TiO2 ternary oxide particles with different content ratios have been prepared by a sol-gel method using metal alkoxides. Only a RuO2-rich specimen was composed of a mixture of rutile-type oxide phase and a metallic phase, while the other specimens were composed of only rutile-type oxide phase after calcination of them in air at 450-degrees-C for 3 h. The comparison of the XRD spectra of these ternary oxide particles with those of ternary oxide films prepared by a conventional dip-coating method on titanium plate substrates suggested that the oxide particles tended to attain more stable state than the oxide films.