Fluorescence spectroscopy is a rapid, cheap, sensitive, specific and non-destructive method suitable for the characterization of autofluorescence-exhibiting lignins. Fluorescence spectral information, treated according to Principal Components Analysis (PCA), was used to study paper pulps from different biological sources. Wheat straw, fiber sorghum and sweet sorghum stalks were pulped with an aqueous ethanol solution under acid or alkali conditions. The results indicated that the fluorescence emission spectra of solid paper pulps through PCA could give information about the origin of the pulp sample and the type of pulping method used. Additional findings included the existence of a good correlation between the fluorescence data and the kappa number, as well as the lignin contents in the pulps, from the various raw materials.