A method for oxidatively brightening and/or dyeing keratin fibers, in particular hair, characterized in that a) a pre-treatment agent that contains at least one 4-morpholinomethyl-substituted silicone of formula, in which A represents a structural unit,, (IIIa), (IIIb), (IIIe) or (IIIf) bound by an-O-, or an oligomeric or polymeric functional group bound by an -O-, containing structural units of formulae,, (IIIa), (IIIb), (IIIe) or (IIIf), or -OH, * represents a bond to one of the structural units,, (IIIa), (IIIb), (IIIe) or (IIIf), or a terminal group B (Si-bound) or D (O-bound), B represents an -OH, -O-Si(CH 3) 3, -O-Si(CH 3) 2 OH or -O-Si(CH 3) 2 OCH 3 group, D represents a -H, -Si(CH 3) 3, -Si(CH 3) 2 OH, -Si(CH 3) 2 OCH 3 group, a, b and c represent integers from 0 to 990, with the proviso a + b + c > 0 m, n and o represent integers from 1 to 990, is applied to the keratin fibers, in particular the hair, b) subsequently, within a period of from one second to 24 hours, after step a) a dye and/or brightening agent is applied to the keratin fibers, which is obtained by mixing a composition, which contains at least one alkalizing agent, with a composition, which contains at least one oxidizing agent in a cosmetic carrier, characterized in that the composition contains at least one acyl pyridinium derivative of formula (Acylpyr-I), in which R1 represents a C 1 -C 6 alkyl group, a C 2 -C 6 alkenyl group, a C 2 -C 6 hydroxyalkyl group, a C 1 -C 6 alkoxy C 2 -C 6 alkyl group, a carboxy C 2 -C 6 alkyl group, an aryl C 1 -C 6 alkyl group, a heteroaryl C 1 -C 6 alkyl group, an aryl group or a heteroaryl group, R2, R3 and R4 each represent, independently of one another, hydrogen, a C 1 -C 6 alkyl group, a halogen atom or a C 1 -C 6 acyl group, with the proviso that at least one of the functional groups R2, R3 and R4 represents a C 1 -C 6 acyl group, and X - represents a physiologically acceptable anion. a) a pre-treatment agent that contains at least one 4-morpholinomethyl-substituted silicone of formula, in which A represents a structural unit,, (IIIa), (IIIb), (IIIe) or (IIIf) bound by an-O-, or an oligomeric or polymeric functional group bound by an -O-, containing structural units of formulae,, (IIIa), (IIIb), (IIIe) or (IIIf), or -OH, * represents a bond to one of the structural units,, (IIIa), (IIIb), (IIIe) or (IIIf), or a terminal group B (Si-bound) or D (O-bound), B represents an -OH, -O-Si(CH 3) 3, -O-Si(CH 3) 2 OH or -O-Si(CH 3) 2 OCH 3 group, D represents a -H, -Si(CH 3) 3, -Si(CH 3) 2 OH, -Si(CH 3) 2 OCH 3 group, a, b and c represent integers from 0 to 990, with the proviso a + b + c > 0 m, n and o represent integers from 1 to 990, is applied to the keratin fibers, in particular the hair, A represents a structural unit,, (IIIa), (IIIb), (IIIe) or (IIIf) bound by an-O-, or an oligomeric or polymeric functional group bound by an -O-, containing structural units of formulae,, (IIIa), (IIIb), (IIIe) or (IIIf), or -OH, * represents a bond to one of the structural units,, (IIIa), (IIIb), (IIIe) or (IIIf), or a terminal group B (Si-bound) or D (O-bound), B represents an -OH, -O-Si(CH 3) 3, -O-Si(CH 3) 2 OH or -O-Si(CH 3) 2 OCH 3 group, D represents a -H, -Si(CH 3) 3, -Si(CH 3) 2 OH, -Si(CH 3) 2 OCH 3 group, a, b and c represent integers from 0 to 990, with the proviso a + b + c > 0 m, n and o represent integers from 1 to 990, b) subsequently, within a period of from one second to 24 hours, after step a) a dye and/or brightening agent is applied to the keratin fibers, which is obtained by mixing a composition, which contains at least one alkalizing agent, with a composition, which contains at least one oxidizing agent in a cosmetic carrier, characterized in that the composition contains at least one acyl pyridinium derivative of formula (Acylpyr-I), in which R1 represents a C 1 -C 6 alkyl group, a C 2 -C 6 alkenyl group, a C 2 -C 6 hydroxyalkyl group, a C 1 -C 6 alkoxy C 2 -C 6 alkyl group, a carboxy C 2 -C 6 alkyl group, an aryl C 1 -C 6 alkyl group, a heteroaryl C 1 -C 6 alkyl group, an aryl group or a heteroaryl group, R2, R3 and R4 each represent, independently of one another, hydrogen, a C 1 -C 6 alkyl group, a halogen atom or a C 1 -C 6 acyl group, with the proviso that at least one of the functional groups R2, R3 and R4 represents a C 1 -C 6 acyl group, and X - represents a physiologically acceptable anion. R1 represents a C 1 -C 6 alkyl group, a C 2 -C 6 alkenyl group, a C 2 -C 6 hydroxyalkyl group, a C 1 -C 6 alkoxy C 2 -C 6 alkyl group, a carboxy C 2 -C 6 alkyl group, an aryl C 1 -C 6 alkyl group, a heteroaryl C 1 -C 6 alkyl group, an aryl group or a heteroaryl group, R2, R3 and R4 each represent, independently of one another, hydrogen, a C 1 -C 6 alkyl group, a halogen atom or a C 1 -C 6 acyl group, with the proviso that at least one of the functional groups R2, R3 and R4 represents a C 1 -C 6 acyl group, and X - represents a physiologically acceptable anion.