So far, the study of the structure of superplasticizers has been carried out on the main component of the cement admixture. This work presents the first structural Raman characterization of a superplasticizer in the complex matrix of a commercial product. In this case, a third-generation (polycarboxylate based) superplasticizer was studied at various experimental conditions (excitation lines: 325, 445, 532, 633, 785, and 1064 nm; and pH values from 3 to 13). The best results were obtained by using the Fourier transformed-Raman technique. Density functional theory calculations at the B3LYP/6-31 G** level of theory were performed to aid in the characterization of the molecular structure of the superplasticizer. The structure of several models with the general structure of polycarboxylates was optimized and the Raman spectra were calculated. Finally, two different structures of the third-generation superplasticizer were determined by comparison of the experimental Raman spectra with the calculated ones. Copyright © 2012 John Wiley & Sons, Ltd.