Textile effluents are highly toxic as they contain a large number of metal complex dyes. The high concentration of such dyes causes many water borne diseases and increases the BOD of the receiving waters. On the other hand, flyash is a major pollutant generated in coal-based thermal power plants and has potentiality for use as an adsorbent. In the present work, adsorption studies were made in treating the dye solutions of methylene blue (M-B)and Congo red (CR) textile dyes by using flyash. Effects of quantity of adsorbent, time of contact, initial effluent concentration, pH and temperature have been investigated experimentally and the results were compared with those obtained by using activated carbon. The first-order adsorption rate constants were determined and found decreasing with temperature. The results obtained were fitted by Langmuir model since monolayer formation observed. Also, Langmuir adsorption isotherm parameters were estimated from the experimental data obtained for both methylene blue and Congo red dyes using both the adsorbents. (c) 2005 Elsevier B.V. All rights reserved.