Process for producing a surface-reacted calcium carbonate comprising the steps of: a) providing an aqueous suspension of calcium carbonate-comprising material, b) providing phosphoric acid in an amount from 1 to 60 wt.-%, based on the total weight of the calcium carbonate-comprising material, c) providing at least one dicarboxylic acid or a corresponding salt thereof, wherein the at least one dicarboxylic acid is selected from the group consisting of maleic acid, malonic acid, malic acid, tartaric acid, optionally substituted with one or more methyl and/or ethyl groups, and mixtures thereof, wherein the at least one dicarboxylic acid or a corresponding salt thereof is provided in an amount from 0.1 to 50 wt.-%, based on the total weight of the calcium carbonate-comprising material, wherein the at least one dicarboxylic acid or a corresponding salt thereof is provided in an amount from 1 to 25 wt.-% based on the total weight of the phosphoric acid, d) adding the phosphoric acid of step b) to the calcium carbonate-comprising material of step a) over a phosphoric acid addition time period Δ t P in the presence of carbon dioxide to form an aqueous suspension of surface-reacted calcium carbonate, wherein the carbon dioxide is formed in-situ by the addition of phosphoric acid and/or is supplied from an external source, and wherein the at least one dicarboxylic acid of step c) or a corresponding salt thereof is added in step d) during the phosphoric acid addition time period Δ t P . a) providing an aqueous suspension of calcium carbonate-comprising material, b) providing phosphoric acid in an amount from 1 to 60 wt.-%, based on the total weight of the calcium carbonate-comprising material, c) providing at least one dicarboxylic acid or a corresponding salt thereof, wherein the at least one dicarboxylic acid is selected from the group consisting of maleic acid, malonic acid, malic acid, tartaric acid, optionally substituted with one or more methyl and/or ethyl groups, and mixtures thereof, wherein the at least one dicarboxylic acid or a corresponding salt thereof is provided in an amount from 0.1 to 50 wt.-%, based on the total weight of the calcium carbonate-comprising material, wherein the at least one dicarboxylic acid or a corresponding salt thereof is provided in an amount from 1 to 25 wt.-% based on the total weight of the phosphoric acid, wherein the at least one dicarboxylic acid is selected from the group consisting of maleic acid, malonic acid, malic acid, tartaric acid, optionally substituted with one or more methyl and/or ethyl groups, and mixtures thereof, wherein the at least one dicarboxylic acid or a corresponding salt thereof is provided in an amount from 0.1 to 50 wt.-%, based on the total weight of the calcium carbonate-comprising material, wherein the at least one dicarboxylic acid or a corresponding salt thereof is provided in an amount from 1 to 25 wt.-% based on the total weight of the phosphoric acid, d) adding the phosphoric acid of step b) to the calcium carbonate-comprising material of step a) over a phosphoric acid addition time period Δ t P in the presence of carbon dioxide to form an aqueous suspension of surface-reacted calcium carbonate, wherein the carbon dioxide is formed in-situ by the addition of phosphoric acid and/or is supplied from an external source, and wherein the at least one dicarboxylic acid of step c) or a corresponding salt thereof is added in step d) during the phosphoric acid addition time period Δ t P . wherein the carbon dioxide is formed in-situ by the addition of phosphoric acid and/or is supplied from an external source, and wherein the at least one dicarboxylic acid of step c) or a corresponding salt thereof is added in step d) during the phosphoric acid addition time period Δ t P . <EOS>