A process for semi-permanent straightening and permanent shaping hair, especially human hair, wherein the semi- permanent straightening comprises the steps of: a. optionally washing the hair with a cleansing composition and towel drying, b. applying to the hair a treatment composition A comprising at least one compound of the general structure and/or a hydrate thereof and/or a salt thereof R-CO-R' Formula wherein R is selected from hydrogen, COOH, CN, optionally substituted C 1 -C 10 alkyl, optionally substituted C 2 -C 10 alkenyl, optionally substituted C 2 -C 10 alkynyl, optionally substituted C 3 -C 10 cycloalkyl, optionally substituted C 6 -C 10 aryl or a 5-10-membered, optionally substituted heteroaryl group, wherein the optional substituents of the alkyl group are selected from halogen, hydroxyl, amino and C 1 -C 4 alkoxy, and the optional substituents of the other groups are selected from halogen, hydroxyl, amino, C 1 -C 4 alkyl and C 1 -C 4 alkoxy and R' is COOH or H and wherein the composition has a pH in the range of 1 to 4 when R' is COOH and in the range of 1 to 6 when R' is H, c. leaving the composition A on the hair for 1 min to 90 min, d. optionally rinsing the hair, e. drying the hair, f. heating the hair to a temperature in the range of 130°C to 230°C, g. optionally washing the hair with a cleansing composition, wherein the permanent shaping comprises the steps of: h. optionally washing and/or shampooing the hair and towel drying, i. optionally, putting hair under tension, j. applying to the hair a ready to use composition obtained by mixing the compositions B and D, wherein the composition B is an aqueous composition comprising one or more reducing agents, one or more alkalizing agents and having a pH in the range from 6.0 to 12.0, wherein the composition D is a composition comprising: 1) one or more carboxylic acids having three or more carboxyl groups and/or their salts, and 2) one or more additional organic acid and/or their salts having one or two carboxyl groups, at a total concentration of 10% to 100% by weight, calculated to the total of the composition D, wherein the ready-to-use composition has a pH in the range of 6 to 12 and comprises the acids and/or its salts at a total concentration in the range of 1.0% to 10.0% by weight, calculated to the total of the ready-to-use composition, k. leaving the composition on the hair for 1 min to 45 min, I. rinsing off the hair with water, m. optionally drying and heating the hair, n. applying to the hair an aqueous composition C comprising one or more oxidizing agents, preferably hydrogen peroxide, and has a pH in the range from 1.5 to 5, and is left on the hair for a period from 1 min to 45 min, o. releasing the tension from hair in case the hair is put under tension in step (i), p. rinsing hair and optionally washing with a cleansing composition. a. optionally washing the hair with a cleansing composition and towel drying, b. applying to the hair a treatment composition A comprising at least one compound of the general structure and/or a hydrate thereof and/or a salt thereof R-CO-R' Formula wherein R is selected from hydrogen, COOH, CN, optionally substituted C 1 -C 10 alkyl, optionally substituted C 2 -C 10 alkenyl, optionally substituted C 2 -C 10 alkynyl, optionally substituted C 3 -C 10 cycloalkyl, optionally substituted C 6 -C 10 aryl or a 5-10-membered, optionally substituted heteroaryl group, wherein the optional substituents of the alkyl group are selected from halogen, hydroxyl, amino and C 1 -C 4 alkoxy, and the optional substituents of the other groups are selected from halogen, hydroxyl, amino, C 1 -C 4 alkyl and C 1 -C 4 alkoxy and R' is COOH or H and wherein the composition has a pH in the range of 1 to 4 when R' is COOH and in the range of 1 to 6 when R' is H, c. leaving the composition A on the hair for 1 min to 90 min, d. optionally rinsing the hair, e. drying the hair, f. heating the hair to a temperature in the range of 130°C to 230°C, g. optionally washing the hair with a cleansing composition, h. optionally washing and/or shampooing the hair and towel drying, i. optionally, putting hair under tension, j. applying to the hair a ready to use composition obtained by mixing the compositions B and D, wherein the composition B is an aqueous composition comprising one or more reducing agents, one or more alkalizing agents and having a pH in the range from 6.0 to 12.0, wherein the composition D is a composition comprising: 1) one or more carboxylic acids having three or more carboxyl groups and/or their salts, and 2) one or more additional organic acid and/or their salts having one or two carboxyl groups, at a total concentration of 10% to 100% by weight, calculated to the total of the composition D, wherein the ready-to-use composition has a pH in the range of 6 to 12 and comprises the acids and/or its salts at a total concentration in the range of 1.0% to 10.0% by weight, calculated to the total of the ready-to-use composition, 1) one or more carboxylic acids having three or more carboxyl groups and/or their salts, and 2) one or more additional organic acid and/or their salts having one or two carboxyl groups, k. leaving the composition on the hair for 1 min to 45 min, I. rinsing off the hair with water, m. optionally drying and heating the hair, n. applying to the hair an aqueous composition C comprising one or more oxidizing agents, preferably hydrogen peroxide, and has a pH in the range from 1.5 to 5, and is left on the hair for a period from 1 min to 45 min, o. releasing the tension from hair in case the hair is put under tension in step (i), p. rinsing hair and optionally washing with a cleansing composition.