Use of a composition of at least one alkoxylated polyethyleneimine of Formula or Formula at least one alkoxylated alkylphenol-aldehyde resin having a repeating structural unit of Formula in which X i for i = 1 to j, 1 to k, 1 to l, 1 to m, 1 to n, 1 to p, 1 to q, 1 to r or 1 to s is independently selected from the group consisting of -CH 2 -CH 2 -O-, -CH 2 -CH(CH 3)-O-, -CH(CH 3)-CH 2 -O-, -CH 2 -C(CH 3) 2 -O-, -C(CH 3) 2 -CH 2 -O-, -CH 2 -CH(C 2 H 5)-O-, -CH(C 2 H 5)-CH 2 -O- and - CH(CH 3)-CH(CH 3)-O-, preferably selected from the group consisting of -CH 2 -CH(CH 3)-O-, -CH(CH 3)-CH 2 -O-, -CH 2 -C(CH 3) 2 -O-, -C(CH 3) 2 -CH 2 -O-, -CH 2 -CH(C 2 H 5)-O-, - CH(C 2 H 5)-CH 2 -O- and -CH(CH 3)-CH(CH 3)-O-, more preferably selected from the group consisting of -CH 2 -CH(CH 3)-O-, -CH(CH 3)-CH 2 -O-, -CH 2 -C(CH 3) 2 -O-, -C(CH 3) 2 -CH 2 -O-, -CH 2 -CH(C 2 H 5)-O- and -CH(C 2 H 5)-CH 2 -O- and most preferably selected from the group consisting of -CH 2 -CH 2 -O-, -CH 2 -CH(C 2 H 5)-O-, -CH(C 2 H 5)-CH 2 -O-, -CH 2 -CH(CH 3)-O- and -CH(CH 3)-CH 2 -O-, and especially selected from the group consisting of -CH 2 -CH 2 -O-, -CH 2 -CH(CH 3)-O- and -CH(CH 3)-CH 2 -O-, x and y are independently zero or a positive integer z is a positive integer of 10 to 80 j, k, l, m, n, p, q, and r are independently zero or a positive integer R 1 is hydrogen or a group -[-X i -] s -H R 2 is a linear or branched C 4 - to C 24 -alkyl group R 3 is hydrogen or a C 1 - to C 4 -alkyl group, wherein s is a positive integer of 3 to 30, with the proviso that - in formula the sum total of x and y is non-zero, - the sum total of j, k, l, m, n, p, q, and r is non-zero, and at least one alkyl-, aryl- or alkylaryl sulfonate or sulfate wherein the weight ratio of the components:: is 0.1 - 100: 0.1 - 100: > 0 - 0.5 for demulsification of mixtures of fuels and water. at least one alkoxylated polyethyleneimine of Formula or Formula at least one alkoxylated alkylphenol-aldehyde resin having a repeating structural unit of Formula in which X i for i = 1 to j, 1 to k, 1 to l, 1 to m, 1 to n, 1 to p, 1 to q, 1 to r or 1 to s is independently selected from the group consisting of -CH 2 -CH 2 -O-, -CH 2 -CH(CH 3)-O-, -CH(CH 3)-CH 2 -O-, -CH 2 -C(CH 3) 2 -O-, -C(CH 3) 2 -CH 2 -O-, -CH 2 -CH(C 2 H 5)-O-, -CH(C 2 H 5)-CH 2 -O- and - CH(CH 3)-CH(CH 3)-O-, preferably selected from the group consisting of -CH 2 -CH(CH 3)-O-, -CH(CH 3)-CH 2 -O-, -CH 2 -C(CH 3) 2 -O-, -C(CH 3) 2 -CH 2 -O-, -CH 2 -CH(C 2 H 5)-O-, - CH(C 2 H 5)-CH 2 -O- and -CH(CH 3)-CH(CH 3)-O-, more preferably selected from the group consisting of -CH 2 -CH(CH 3)-O-, -CH(CH 3)-CH 2 -O-, -CH 2 -C(CH 3) 2 -O-, -C(CH 3) 2 -CH 2 -O-, -CH 2 -CH(C 2 H 5)-O- and -CH(C 2 H 5)-CH 2 -O- and most preferably selected from the group consisting of -CH 2 -CH 2 -O-, -CH 2 -CH(C 2 H 5)-O-, -CH(C 2 H 5)-CH 2 -O-, -CH 2 -CH(CH 3)-O- and -CH(CH 3)-CH 2 -O-, and especially selected from the group consisting of -CH 2 -CH 2 -O-, -CH 2 -CH(CH 3)-O- and -CH(CH 3)-CH 2 -O-, x and y are independently zero or a positive integer z is a positive integer of 10 to 80 j, k, l, m, n, p, q, and r are independently zero or a positive integer R 1 is hydrogen or a group -[-X i -] s -H R 2 is a linear or branched C 4 - to C 24 -alkyl group R 3 is hydrogen or a C 1 - to C 4 -alkyl group, wherein s is a positive integer of 3 to 30, with the proviso that - in formula the sum total of x and y is non-zero, - the sum total of j, k, l, m, n, p, q, and r is non-zero, and X i for i = 1 to j, 1 to k, 1 to l, 1 to m, 1 to n, 1 to p, 1 to q, 1 to r or 1 to s is independently selected from the group consisting of -CH 2 -CH 2 -O-, -CH 2 -CH(CH 3)-O-, -CH(CH 3)-CH 2 -O-, -CH 2 -C(CH 3) 2 -O-, -C(CH 3) 2 -CH 2 -O-, -CH 2 -CH(C 2 H 5)-O-, -CH(C 2 H 5)-CH 2 -O- and - CH(CH 3)-CH(CH 3)-O-, preferably selected from the group consisting of -CH 2 -CH(CH 3)-O-, -CH(CH 3)-CH 2 -O-, -CH 2 -C(CH 3) 2 -O-, -C(CH 3) 2 -CH 2 -O-, -CH 2 -CH(C 2 H 5)-O-, - CH(C 2 H 5)-CH 2 -O- and -CH(CH 3)-CH(CH 3)-O-, more preferably selected from the group consisting of -CH 2 -CH(CH 3)-O-, -CH(CH 3)-CH 2 -O-, -CH 2 -C(CH 3) 2 -O-, -C(CH 3) 2 -CH 2 -O-, -CH 2 -CH(C 2 H 5)-O- and -CH(C 2 H 5)-CH 2 -O- and most preferably selected from the group consisting of -CH 2 -CH 2 -O-, -CH 2 -CH(C 2 H 5)-O-, -CH(C 2 H 5)-CH 2 -O-, -CH 2 -CH(CH 3)-O- and -CH(CH 3)-CH 2 -O-, and especially selected from the group consisting of -CH 2 -CH 2 -O-, -CH 2 -CH(CH 3)-O- and -CH(CH 3)-CH 2 -O-, x and y are independently zero or a positive integer z is a positive integer of 10 to 80 j, k, l, m, n, p, q, and r are independently zero or a positive integer R 1 is hydrogen or a group -[-X i -] s -H R 2 is a linear or branched C 4 - to C 24 -alkyl group R 3 is hydrogen or a C 1 - to C 4 -alkyl group, wherein s is a positive integer of 3 to 30, with the proviso that - in formula the sum total of x and y is non-zero, - the sum total of j, k, l, m, n, p, q, and r is non-zero, and - in formula the sum total of x and y is non-zero, - the sum total of j, k, l, m, n, p, q, and r is non-zero, at least one alkyl-, aryl- or alkylaryl sulfonate or sulfate wherein the weight ratio of the components:: is 0.1 - 100: 0.1 - 100: > 0 - 0.5 for demulsification of mixtures of fuels and water. wherein the weight ratio of the components:: is 0.1 - 100: 0.1 - 100: > 0 - 0.5 for demulsification of mixtures of fuels and water.