The study was focused on the usability of olive tree leaves fallen during olive harvesting in dyeing and antibacterial finishing of cotton fabrics for cleaner production. Valorizing these waste (olive tree leaves) obtained during harvesting and using them in textile treatment processes would ensure a cleaner and more sustainable production. For this aim, olive tree leaves were subjected to an extraction process before their use in dyeing as well as directly use without any previous extraction. Six mordanting agents were also tested. Dyeing was done at two different temperatures (80 degrees C and 100 degrees C), and the liquor ratio was 1:60. First, the treated samples were tested for fastness and color variety. It was observed that sufficient fastness and color variety can be produced by using olive tree leaves with or without mordanting agents. Antibacterial tests were also conducted for samples dyed without mordanting agents. The antibacterial effects of mordants were also tested. The samples were tested against Escherichia coli and Staphylococcus aureus. It was found that mordanting agents provide significant antibacterial efficiency against both tested bacteria and minimum of 90% bacterial reduction was observed. Using olive tree leaves without any mordants also demonstrated antibacterial efficiency and better bacterial reductions were observed for both bacterial species in dyeings at 80 degrees C. The reason of antibacterial efficiency caused by the olive tree leaves were investigated by ICP-MS analysis. Addition to the oleuropein content of the extract, the elements detected by ICP-MS assumed as responsible for the bacterial reduction. (C) 2020 Elsevier Ltd. All rights reserved.