The purpose of this study was to establish the potential of inexpensive and locally available biomaterial, that is, lignocellulosic waste of Citrus sinensis as biosorbent to remove reactive anthraquinone dyes from aqueous solution. The effects of immobilisation and chemical treatment of biosorbent were also explored for the enhanced sorption of dyes. Biosorbent was chemically treated with organic and inorganic reagents of which acetic acid augmented the sorption capacities for Reactive blue 19 and Reactive blue 49 attaining equilibrium in 60?min. While immobilisation of biosorbent into calcium alginate beads reduced the sorption capacity and the time to achieve equilibrium was prolonged up to 120?min. Sorption of both reactive dyes was found to be dependent on pH of media and maximum removal was observed at pH 2. The sorption process was fast and the data followed pseudo-second-order kinetic rate equation (R2?=?0.99). The equilibrium data were also fitted to Freundlich, Langmuir and Temkin isotherms. The mechanism of sorption was found to be physiosorption. FTIR analysis and SEM imaging of biosorbent were also carried out to study functional groups involved and morphological changes at the surface of biomass. (c) 2011 Canadian Society for Chemical Engineering