Process for the preparation of a hardening accelerator composition by reaction of a water-soluble calcium compound with a water-soluble silicate compound, the reaction of the water-soluble calcium compound with the water-soluble silicate compound being carried out in the presence of an aqueous solution which contains a water-soluble comb polymer suitable as a plasticizer for hydraulic binders, wherein the water-soluble comb polymer suitable as a plasticizer for hydraulic binders is present as a copolymer which is produced by free radical polymerization in the presence of a phosphorylated monomer and a (meth)acrylic acid ester based polyether macromonomer, so that a structural unit is produced in the comb polymer by incorporation of the phosphorylated acid monomer in the form of polymerized units, which structural unit is in accordance with general formula where R 1 are identical or different and are independently of one another represented by H and/or a non-branched chain or branched C 1 - C 4 alkyl group, preferably R 1 is methyl, where n = 2, 3 or 4, preferably 2, M 1 and M 2 are identical or different and independently from one another H and/or a cation equivalent, and that a structural unit is produced in the comb polymer by incorporation of the (meth)acrylic acid ester based polyether macromonomer in the form of polymerized units, which structural unit is in accordance with general formula, where R 2 is identical or different and independently of one another, is represented by H and/or a non-branched chain or branched C 1 - C 4 alkyl group, preferably R 2 is methyl, A are identical or different and are represented by C x H 2x where x = 2, 3, 4 and/or 5, preferably 2, with the proviso that at least 85 mol % of A are C 2 H 4, a are identical or different and are represented by an integer from 65 to 160 preferably 90 to 140, R 3 are identical or different and independently of one another are represented by H and/or a non-branched chain or a branched C 1 - C 4 alkyl group, preferably a C 1 - C 4 alkyl group. R 1 are identical or different and are independently of one another represented by H and/or a non-branched chain or branched C 1 - C 4 alkyl group, preferably R 1 is methyl, where n = 2, 3 or 4, preferably 2, M 1 and M 2 are identical or different and independently from one another H and/or a cation equivalent, and that a structural unit is produced in the comb polymer by incorporation of the (meth)acrylic acid ester based polyether macromonomer in the form of polymerized units, which structural unit is in accordance with general formula, R 2 is identical or different and independently of one another, is represented by H and/or a non-branched chain or branched C 1 - C 4 alkyl group, preferably R 2 is methyl, A are identical or different and are represented by C x H 2x where x = 2, 3, 4 and/or 5, preferably 2, with the proviso that at least 85 mol % of A are C 2 H 4, a are identical or different and are represented by an integer from 65 to 160 preferably 90 to 140, R 3 are identical or different and independently of one another are represented by H and/or a non-branched chain or a branched C 1 - C 4 alkyl group, preferably a C 1 - C 4 alkyl group.