Staghorn sumac (Rhus typhina) is an alien invasive plant. The influence of the dye extraction process from staghorn sumac fruit and the pre-treatment of cotton fabric on its dyeability was studied in the diploma thesis. The dye was extracted in water and alcohol. Samples of cotton fabric were pre-treated with the cationic agent DENIMCOL FIX-OS and soya milk. The dyeing was performed on untreated and pre-treated samples with the exhaustion method at two concentrations of each dye. The colour value of the dyed samples before and after the washing was measured with a spectrophotometer; moreover, colour fastness to light and rubbing was determined. The results show that the dyeing with water extract gives brighter colours than the dyeing with alcohol extract. Furthermore, samples dyed with water extract are darker, redder and yellower. A higher concentration of the extract causes darker, redder and yellower colouring of the cotton fabric. Pre-treated fabrics are darker, less red and yellower than untreated fabrics. Dyed samples had poor colour fastness to washing, good colour fastness to light and excellent colour fastness to rubbing.