The invention relates to a process for the preparation of a triaryl phosphate ester composition comprising a. reacting a phosphorous oxyhalide with a (C1-C15-alkyl)phenol to obtain a first product; b. reacting the first product with phenol to obtain a triaryl phosphate ester composition; wherein in step a., for every mol of phosphorous oxyhalide 1.3 to 1.6 mols of (C1-C15-alkyl)phenol are used. The invention also relates to a triaryl phosphate ester composition obtainable according to the process of the invention.