The dyeing of cellulosic fibers with disperse and natural dyes was attempted using supercritical carbon dioxide (CO2SCF) as solvent system. The dye uptake was strongly increased if cotton was pretreated with polyethylene glycol (PEG), a known plasticizing agent of cellulose, while reasonable wet-washing and light fastness properties were achieved if PEG-treated cotton was dyed in CO2SCF with disperse dyes included in benzamide crystals. This might be a consequence of partial occlusion of cellulose pores by benzamide, forming hydrogen bonds with cotton and PEG.