The low-pressure cold microwave (MW) plasma is shown as an efficient method to increase acidity of the ACF within less than 1 min treatment without affecting the fiber morphol. and strength. The ion-exchange capacity was 1.6 times higher compared to the non-treated ACF sample. Selective removal of the carboxylic groups from the ACF surface by the air-MW-plasma allows to keep the phenolic groups intact. Palladium was deposited on ACF from [Pd(NH3)4]Cl2 soln. via ion-exchange with the protons of the phenolic surface groups. Surface phenolic groups were able to chem. anchor Pd in cationic form, leading after redn. in H2 to small Pd Deg nanoparticles (<3 nm). The Pd dispersion was measured by CO pulse adsorption and confirmed by the TEM anal. Heating of the Pd/ACF catalysts in H2 at 573-773 K is necessary to reduce Pd(II) to Pd Deg. This redn. can be also achieved by the H2-MW-plasma treatment in less than 1 min with the corresponding saving of energy. [on SciFinder (R)]