A modern version of the indirect ex-cell electrolytic oxidn. of arom. compds. is presented in which: (1) a slurry of Mn2(SO4)3 in concd. H2SO4 is used as O carrier in the presence of a mixt. of catalysts to increase the current efficiency for the electrochem. oxidn. of Mn2+ and the selectivity of the chem. reaction; (2) the electrolyte is purified with an optimum mode before electroregeneration; (3) a new simple electrochem. reactor was developed for an economical electroregeneration of Mn3+. [on SciFinder (R)]