Linseed oil based polymers from cationic and thermal polymerizations have been investigated quantitatively through H-1 NMR and FTIR spectroscopic analysis. The solubility of the samples ranges from 22 to 37% for cationic samples and from 4.23 to 53% for thermal samples. The content of the grafted linseed oil calculated from H-1 NMR results ranges from 22.9 to 43.0% and from 0 to 10% for cationic and thermal samples. The grafted linseed oil contents from FTIR are 18.2-45.4% and 0-10.7% for cationic and thermal samples. The values obtained through quantitative H-1 NMR and FTIR spectroscopic analysis methods are consistent and can be applied to other polymers also.