The invention relates to compositions containing A) at least one polymer selected from the group of aromatic polycarbonates and aromatic polyester carbonates and B) at least one Brønsted-acidic compound selected from the group consisting of compounds of general formulae (I) and (II) (R1)y1-N—[R2-COOH]x1  (I) [HOOC—R2]x2(R1)y2N—(R3)-N(R1)y3[R2-COOH]x3  (II) wherein R1 represents optionally functionalized or heteroatom-substituted alkyl, aryl or cycloalkyl, R2 represents C1- to C8-alkylene or C2- to C8-alkylidene, R3 represents —(CH2)n—, —(CH2)n[O(CH2)n]m— or —(CH2)n[NR4(CH2)n]m—, n is an integer, m is an integer, R4 represents optionally functionalized or heteroatom-substituted alkyl, aryl or cycloalkyl, x1 is an integer between 1 and 3, x2 and x3 are respectively 1 or 2, and y1 is given by the formula y1=3−x1, y2 by the formula y2=2−x2, y3 by the formula y3=2−x3, and wherein in compounds having a plurality of radicals R1 and/or R2 these may independently of one another represent different or identical radicals having the abovementioned definitions, and also to a process for producing compositions using components A, B and optionally further components, wherein at least one of the employed components is alkaline or contains alkaline constituents, to compositions obtained by this process and to the use of the compositions for producing molded articles and to the molded articles themselves.