This dataset contains all terpolymerisation data on which the publication "In-line Raman chemometrics for quantitative monitoring in the spectral challenging butyl acrylate - styrene - acrylic acid terpolymerisation." is based. Experimental data (.xlsx), Raman spectra (.spc), PEAXACT models (.pxm), GC offline measurements (.pdf) and additional text (.txt) are provided. In the second version of this dataset the BA homopolymerization data was added.