This International Standard specifies procedures for the quantitative determination of the microstructure of the butadiene units and the content of styrene units in solution-polymerized SBR (S-SBR) by 1H-NMR spectrometry as an absolute method and by IR spectrometry as a relative method. The styrene content is expressed in mass % relative to the whole polymer. The 1,4-trans, 1,4-cis and 1,2-vinyl contents are expressed in mol % relative to the butadiene units. NOTE IR spectrometry can also give absolute values of microstructure by calibration with S-SBRs of known absolute microstructure obtained by 1H-NMR spectrometry