Reactive Blue 15 (RB 15) adsorption on the Turkish Sepiolite was carried out by batch equilibrium technique. IR spectrum and surface area measurement of the composite of dye-sepiolite (Turkish) pointed out that dye species replaced partly the zeolitic water to form hydrogen bond with bound water and adsorbed to the channels sites. The effects of temperature, pH and ionic strength on adsorption of dye molecules were investigated and the nature of adsorption process was determined by calculating ΔH, ΔS and ΔG values. The adsorbed amount increased with increase in temperature, but that for high pH values decreased for the adsorption of reactive dye. © 2008 Elsevier B.V. All rights reserved.