NOVELTY - An aqueous formulation comprises (by wt.) : (a) a mediator (0.1-20%); (b) a peroxide compound (0.1-20%); and (c) an aqueous solution of a pH stabilizer (60-99.8%), with mediator (a) being a benzene ring-condensed N-heterocyclic compound and with the formulation being free of enzymes.    USE - Claimed use of the formulation is as a component in enzymatic bleaching systems, the systems preferably also containing an enzyme with peroxidase or laccase activity. Specifically claimed applications are in : (i) decoloring of dyes in waste water; (ii) washing of differently-colored textiles; (iii) bleaching of lignin-containing materials, especially in papermaking; (iv) treatment of waste water from papermaking; (v) enzymatic polymerisation of lignin-containing materials; and (vi) decoloring of non-bonded excesses of dyes present after textile dyeing. Application (vi) is especially for use with reactive dyes, the dyed material being contacted in one or more of the rinsing stages with an enzymatic 2-component bleaching system containing the above formulation as one component, with this formulation and the enzyme component being added separately to the rinsing liquid, the aqueous formulation preferably being added first.    ADVANTAGE - The formulations are storage-stable and their use in the removal of excesses of dyes from dyed textiles can be effected on an industrial scale more easily than is the case with the 1-component compositions of which contain enzymes as well as oxidizing agents and mediators similar to those used above..    DETAILED DESCRIPTION - Mediator (a) being a benzene ring-condensed N-heterocyclic compound of formula (I).    M=H, alkali (especially Na or K), alkaline earth (especially Ca or Mg), ammonium or 1-4C alkyl- or alkanol-ammonium;    R1 - R4=H, halogen (especially F, Cl or Br), OH, formyl, amino, NO2, 1-12C alkyl, 1-6C alkoxy, carbonyl-1-6C alkyl, phenyl, benzyl, phenyloxy, -COOR5, -SO2OR5, -SO2NH2, -NHSO2, -CONH2, -PO(OR5)2, -PO2(OR5) or -OPO(OR5)2;    X=-N=N-, (-N=CR6-)m, (-CR6=N-)m or (-CR7=CR8-)m;    m=1 or 2;    R5=H, alkali (especially Na or K), alkaline earth (especially Ca or Mg), ammonium or 1-4C alkyl- or alkanol-ammonium, 1-18 (especially 3-10)C alkyl or -(CH2CH2O-)x;    x=1-25 (especially 3-15); and    R6 - R8=as for R1 - R4