NOVELTY - Forming electrochemical catalysts of fuel cells based on polymer electrolytes involves maximizing specific surface area of support using high output ultrasonic wave; preparing precursor solution formed with micelle containing precursor ions using metal precursor and surfactant respectively; injecting the solution into carrier dispersion to which ultrasonic wave is applied; allowing micelle to be adsorbed on support surface; forming nuclei of metal particles by injecting reducing agent; stopping the wave and growing size of metal particles; cooling; cleaning micelle and drying.    USE - For forming electrochemical catalysts of fuel cells based on polymer electrolytes useful for a membrane-electrode assembly, particularly electrolyte membrane electrode assembly (claimed).    ADVANTAGE - The process is more environmental friendly and economical as well as uniformly supports a large amount of metal nanoparticles irrespective of a kind of metal without agglomeration, as compared to the prior art, and thus provides electrochemical catalysts for a polymer electrolyte fuel cell with more improved electrochemical characteristics than the prior art as well as the commercial product. Also, the process has high catalyst activity, uses a small amount of toxic solvent, and is appropriate for mass production since it uses a small amount of toxic solvent and does not require a high-temperature hydrogen annealing.    DETAILED DESCRIPTION - Forming electrochemical catalysts of fuel cells based on polymer electrolytes to uniformly disperse metal particles in a support involves: a) maximizing a specific surface area of support using high output ultrasonic wave after mixing the support and a solvent; b) preparing a precursor solution formed with a micelle containing precursor ions by using metal precursor and surfactant separately; c) injecting the precursor solution manufactured in (b) into the carrier dispersion to which the high output ultrasonic wave of the step (a) is applied and allowing the micelle to be adsorbed on the surface of the support; d) forming nuclei of metal particles by injecting a reducing agent at 30-70 degrees C; e) stopping the high output ultrasonic wave and growing the size of metal particles to 2-5 nm by raising temperature up to 80-100 degrees C; f) rapid cooling; g) cleaning the micelle surrounding the metal particles; and h) drying.    DESCRIPTION OF DRAWING(S) - The figure shows a process diagram of manufacturing catalysts for a polymer electrolyte fuel cell.