There is a need to explore effective and green approaches to enhancing the ability to use chitosan for contaminant removal for practical implementation of this technology. In the present study, glow discharge plasma (GDP), which has thus far been studied for degradation of contaminants, was used for the first time to pre-treat chitosan for dye removal in aqueous solution. The results show that the GDP treatment changed the morphology and crystallinity of chitosan particles, and the number of -CH2 and -CH3 groups in the chitosan samples increased. Various pretreatment parameters, including discharge current and time, played significant roles in the chitosan modification. It is observed that dye uptake in GDP-modified chitosan was faster than adsorption in untreated chitosan. The maximum adsorption by chitosan followed the order of untreated chitosan < modified chitosan (GDP current: 50 mA) < modified chitosan (GDP current: 120 mA), implying that the chitosan modified by GDP had a higher maximum adsorption capacity in comparison with the untreated chitosan. A possible mechanism is proposed. These results show that GDP may be an attractive pretreatment technology for environmental adsorption materials. (C) 2011 Elsevier B.V. All rights reserved.