TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Process: The process includes, prior to providing the treated particulate carbon, providing a solution of a ruthenium reagent containing ruthenium having a valency of less than (IV); and adding the ruthenium reagent solution to the platinum reagent solution. The ruthenium reagent solution is added to the platinum solution at a rate greater than 0.3 millimoles/minute. A portion of the oxidizing agent is added to the platinum solution simultaneously with the addition of the ruthenium reagent solution. The platinum reagent is formed by providing an aqueous chloroplatinic acid solution, and adding sodium hydrogen sulfite to the aqueous chloroplatinic acid solution to form platinum sulfite acid. The process further involves adding to the chloroplatinic acid solution a suspension containing 0.001-2 wt.% dispersant or surfactant, based on the total combined weight of solids. The carbon is treated. The treatment involves contacting the carbon with an agent from oxygen gas, hydrogen peroxide, organic peroxides or ozone; or contacting the carbon with an agent from oxidizing acids.Preferred Component: The catalyst further comprises ruthenium. The amount of the platinum is 50-90 (preferably 60-80) wt.% of the total weight of the platinum and the carbon support. The agglomerate volume is less than 1.65 nm3/nm2. The oxidizing acid is nitric acid, perchloric acid, chloric acid, permanganic acid, or chromic acid. The carbon support has oxygen content of 0.1-5 wt.%, based on the weight of the carbon. The total amount of the platinum and the ruthenium is 50-90 (preferably 60-80) wt.% of the total weight of the platinum, the ruthenium, and the carbon support. The catalyst comprises platinum (20-90, preferably 60-80 wt.%). The ruthenium reagent is a water-soluble ruthenium (III) species. It is preferably ruthenium chloride (most preferably), ruthenium nitrosyl nitrate, or ruthenium nitrosyl sulfate. The platinum reagent is a water-soluble platinum (II) salt. It is preferably platinum sulfite acid, ammonium tetrachloroplatinate (II), potassium tetrachloroplatinate (II), or water-soluble platinum (II) phosphine complexes. The oxidizing agent is hydrogen peroxide, oxygen gas, or ozone.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The oxidizing agent can be an organic peroxide.    TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Component: The substrate is an ion exchange membrane or a gas diffusion backing. The electrocatalyst coating composition further includes a binder, or a solvent.    TECHNOLOGY FOCUS - POLYMERS - Preferred Component: The ion exchange membrane is the acid form of a perfluorinated sulfonic acid polymer. The binder is an ion exchange polymer EXAMPLE - Chloroplatinic acid solution (34.55 g) and water (500 ml) were added to a 10 L container placed onto a large magnetic stirring plate. A 10-wt.% aqueous suspension containing Daxad 15LS (RTM) dispersant was added to the chloroplatinic acid solution. Sodium hydrogen sulfite (17.65 g) was added, and stirred for 5 minutes. The pH was adjusted to 5 using dilute sodium carbonate solution. A 30-wt.% hydrogen peroxide (858 ml) was added. A 1.81 wt.% ruthenium chloride solution (78.64 g) was added for 15 minutes. Tergitol TM 15-S-9 (RTM) surfactant (0.005 g) was then added. Vulcan XC72R powder was pretreated by slurrying the powder (60.2 g) with 2% nitric acid. The material was refluxed for 5.5 hours, filtered on a 2 micron filter, and then dried in a vacuum oven at 100 degreesC for 5 hours. This material (1.69 g) was used in the reaction. The result demonstrated that rapid ruthenium chloride addition rates (0.94 mmoles ruthenium/minute), coupled with a treated carbon support and in the presence of a surfactant, contributed favorably for the formation of a non-agglomerated catalyst powder, as indicated by the 0.00 nm3/nm2 response.