NOVELTY - A catalyst-polymer liquid dispersion (LD) comprises: (i) catalyst particles; (ii) polymer particles consisting of at least one (per)fluoro sulfonyl fluoride polymer; and (iii) an aqueous suspending medium.    USE - As a catalyst-polymer liquid dispersion useful for preparing catalytic ionomeric ink and catalyst coated membrane (claimed) for membrane electrode assembly in a fuel cell.    ADVANTAGE - The catalyst-polymer dispersion provides the catalytic inks and catalyst coated membranes having improved conductivity, hydrophilicity and electrochemical performance, when used in a fuel cell. The preparation of the catalytic inks is simple and lower in cost.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) preparing (M1) the catalyst-polymer liquid dispersion (LD) involving: (a) mixing an aqueous latex of polymer particles with an aqueous suspension of catalyst particles so as to obtain a catalyst-polymer liquid dispersion (LD) comprising the liquid suspending medium of the latex; (b) removing the liquid so as to isolate the solid constituent of the liquid dispersion (LD); optionally, (c) washing the solid with pure water; optionally, (d) drying the solid and, optionally, grinding it, so as to obtain a smooth powder; and (e) dispersing the solid into pure water;    (2) preparing (M2) a catalyst coated membrane precursor (CCMP), involving: (a1) applying to the surface(s) of the membrane the catalyst-polymer liquid dispersion (LD), where the membrane is a film consisting of at least one (per)fluoro sulfonyl fluoride polymer in the -SO2F form; (b1) removing the liquid so as to form a multilayer structure comprising coating solid layers adhering to the surfaces of the membrane, where the coating solid layer(s) comprise catalyst particles and polymer particles, the polymer particles consisting of at least one (per)fluoro sulfonyl fluoride polymer; optionally, (c1) hot pressing the multilayer structure;    (3) preparing (M3) a catalyst coated membrane (CCM) involving: (a2) applying to the surface(s) of a membrane the catalyst-polymer liquid dispersion (LD), where the membrane is a film consisting of at least one (per)fluoro sulfonyl fluoride polymer in the -SO2F, -SO3H and/or -SO3M form; (b2) removing the liquid so as to form a multilayer structure comprising coating solid layer(s) adhering on the surface(s) of the membrane, where the coating solid solid layer(s) comprising catalyst particles and polymer particles, the polymer particles consisting of at least one (per)fluoro sulfonyl fluoride polymer in the -SO2F form; optionally, (c2) hot pressing the multilayer structure; (d2) transforming the sulfonyl -SO2F groups present in the multilayer structure into sulfonate -SO3M or sulfonic -SO3H groups;    (4) preparing (M4) a catalytic ionomeric ink (CII) involving: (a3) removing any liquid from the catalyst-polymer liquid dispersion (LD) so as to isolate its solid constituent, the solid constituent comprising catalyst and polymer particles; optionally, (b3) washing the solid with pure water, drying and grinding it so as to obtain the solid in the form of a smooth powder; (c3) treating the solid with an aqueous strong base so as to transform the sulfonyl (-SO2F) groups of the polymer particles into sulfonate (-SO3M) groups; (d3) removing the aqueous phase to isolate the solid and washing the solid with pure water; (e3) treating the solid with an aqueous strong acid so as to transform the sulfonate (-SO3M groups into sulfonic (-SO3H) groups; (f3) removing the aqueous phase to isolate the solid, and washing the solid with pure water; optionally, (g3) drying and grinding the solid to obtain a smooth powder; and (h3) dispersing the solid in a hydro-alcoholic liquid phase so as to obtain a slurry; and    (5) preparing (M5) a catalyst coated membrane (CCM-CII), involving: (a4) applying to the surface(s) of a membrane the catalytic ionomeric ink (CII) prepared according to the method (M3), where the membrane is a film consisting of at least one (per)fluoro sulfonyl fluoride polymer in the (-SO3H) form; (b4) removing the liquid so as to form a multilayer structure comprising coating solid layer(s) adhering on the surface(s) of the membrane, the coating solid layer(s) comprising catalyst particles and polymer particles, the polymer particles consisting of at least one (per)fluoro sulfonyl fluoride polymer in the (-SO3H) form; and optionally (c4) hot pressing the multilayer structure.    M=metal.