Silica-based fly ash (FA) received from the National Thermal Power Corporation (NTPC), India has been utilized for determining its dye-adsorption capacity. The dye adsorption using the NTPC-FA has been examined by varying the initial methylene blue dye concentration (7.5–150 μM) and initial solution-pH (2.5–11.5). The dye-adsorption capacity of NTPC-FA has been found to be 0.43 mg/g. To increase the dye-adsorption capacity, the NTPC-FA is subjected to the hydrothermal treatment and typical washing cycles without and with the coating of sol–gel derived anatase-titania. The hydrothermally treated NTPC-FA and hydrogen titanate–silica composite thus obtained exhibit dye-adsorption capacity higher than that of NTPC-FA.