The aim of this work is to study the properties of an activated carbon prepared from apricot stones by carbonisation for 1 h at 700 degrees C and chemical activation with a mixture of H3PO4 + HNO3 and compared to a commercial activated carbon. The adsorbent materials were characterised with FTIR spectroscopy, XRD, SEM/EDX and surface chemistry. The maximum uptake of MB and MO onto the ASAC and CAC under optimised conditions was determined to be 99.5%. The absorption processes of MB and MO by ASAC and CAC were endothermic and exothermic, respectively. Acidic conditions promote the transfer of anionic dye (MO) molecules onto the ASAC and CAC surface by electrostatic attraction. The adsorbents were better able to remove the cationic dye than the anionic dye. The competitive adsorption of dyes favoured the MB on ASAC and CAC in the mixture solution. The Langmuir isotherm model and the pseudo-second order kinetic model were observed to fit the adsorption data well. The mechanism of the adsorption process was determined based on an intraparticle diffusion model. The results of this study will be useful for future scale-up using this apricot stone material as a low-cost adsorbent for the removal of cationic and anionic dyes. (C) 2015 Taiwan Institute of Chemical Engineers.