AbstractPapyrus, produced from the white pith of Cyperus papyrus L., has been used for millennia as the major writing support by ancient cultures, but there was no continuous papyrus production until modern times. Therefore, papyrus production had to be rediscovered. Modern Egyptian papyrus producers claim that their sheets possess ‘the same physical and chemical properties as ancient papyri’. To study if this is accurate, commercially available papyrus sheets were compared to ancient papyri and papyri produced according to Pliny’s historic description. Material characterization was performed with a focus on the potentially color-bearing lignin. Two-dimensional nuclear magnetic resonance spectroscopy, derivatization followed by reductive cleavage, and pyrolysis–gas chromatography/mass spectrometry were complemented with microscopy and tests for surface pH and sodium content. The lignin data in the native pith and commercial sheets were compared to 10 ancient samples from the Papyrus Museum Vienna. The analytical data clearly show the involvement of a strong alkaline treatment followed by chlorine bleaching for commercial papyri, as expressed by higher pH values, altered lignin structures, and chlorinated lignin compounds. The inclusion of an alkaline step in ancient papyrus manufacture is discussed but dismissed, since the alkali-treatment causes a huge decrease in lignin content, that was not found for the analysed ancient specimen. We assume that this additional treatment was introduced to obtain yellowish papyrus sheets meeting optical expectations of modern spectators. Linguistic and art historic evidence indicates that such a step would not have made sense in antiquity, since it was desired to produce white papyri.