NOVELTY - Supported catalyst (10) (I) prepared by: dissolving cation exchange polymer (13) in a solvent; mixing obtained solution containing the cation exchange polymer with catalytic metal precursor (12) or solution containing the metal precursor; heating obtained mixture, adjusting pH of the mixture to predetermined range; adding reducing agent to obtained resultant and stirring to reduce the metal precursor; mixing obtained another resultant with catalyst support; adding precipitating agent to the mixed another resultant; and filtering and drying obtained precipitates to obtain (I), is new.    USE - (I) is useful in an electrode of fuel cell (claimed), preferably direct methanol fuel cell (for portable devices, such as portable computers, phones, personal digital assistants, portable media players, and/or devices), and other fuel cells comprising phosphoric acid fuel cell and proton exchange membrane fuel cell. (I) is useful as catalyst for various chemical reactions, such as hydrogenation, dehydrogenation, coupling, oxidation, isomerization, decarboxylation, hydrocracking, and/or alkylation,    ADVANTAGE - The process provides highly dispersed supported catalyst containing metal particles with reduced particles size.    DETAILED DESCRIPTION - Supported catalyst (10) (I) prepared by either: dissolving cation exchange polymer (13) in a solvent, mixing obtained solution containing the cation exchange polymer with catalytic metal precursor (12) or solution containing the metal precursor, heating obtained mixture, adjusting pH of the mixture to predetermined range, adding reducing agent to obtained resultant and stirring to reduce the metal precursor, mixing obtained another resultant with catalyst support, adding precipitating agent to the mixed another resultant, and filtering and drying obtained precipitates to obtain (I); or producing from a catalytic metal precursor, catalytic metal particles having an average size of 2-5 nm; and mixing the catalytic metal particles with the catalyst support, such that the catalyst support supports the catalytic metal particles, is new. An INDEPENDENT CLAIM is included for a fuel cell comprising: an anode to which fuel is supplied and which includes an anode catalyst layer; a cathode to which an oxidant is supplied and which includes a cathode catalyst layer; and an electrolyte membrane disposed between the cathode and anode, where the anode catalyst layer and/or the cathode catalyst layer includes (I).    DESCRIPTION OF DRAWING(S) - The figure shows a schematic diagram of a supported catalyst.    Supported catalyst (10)    Porous catalyst support (11)    Catalytic metal particles (12)    Cation exchange polymer. (13)