Adsorption is an important process in wastewater treatment, and conversion of waste materials to adsorbent offers a solution to high material cost related to the use of commercial activated carbon. This study investigated the adsorption behaviour of Reactive Black 5 (RB5) and methylene blue (MB) onto activated carbon produced from textile sludge (TSAC). The activated carbon was synthesized through chemical activation of precursor followed with carbonization at 650 degrees C under nitrogen flow. Effects of time (0-200 min), pH (2-10), temperature (25-60 degrees C), initial dye concentration (0-200 mg.L-1), and adsorbent dosage (0.01-0.15 g) on dye removal efficiency were investigated. Preliminary screening revealed that TSAC synthesized via H2SO4 activation showed higher adsorption behaviour than TSAC activated by KCI and ZnCl2. The adsorption capacity of TSAC was found to be 11.98 mg.g(-1) (RB5) and 13.27 mg.g(-1) (MB), and is dependent on adsorption time and initial dye concentration. The adsorption data for both dyes were well fitted to Freundlich isotherm model which explains the heterogeneous nature of TSAC surface. The dye adsorption obeyed pseudo-second order kinetic model, thus chemisorption was the controlling step. This study reveals potential of textile sludge in removal of dyes from aqueous solution, and further studies are required to establish the applicability of the synthesized adsorbent for the treatment of waste water containing toxic dyes from textile industry. (C) 2017 The Chemical Industry and Engineering Society of China. and Chemical Industry Press. All rights reserved.