Surfactants are organic pollutants that are environmentally hazardous for aquatic and human life. A variety of methods are used for the removal of surfactants but adsorption is the most suitable method due to high efficiency, simple operation and economical. This paper describes the adsorption of an anionic surfactant sodium dodecylbenzenesulfonate (SDBS) using fly ash as adsorbent. The adsorbent dosage of 10 g/L and contact time of 5 hours were optimum for the adsorption of SDBS. The maximum adsorption capacity of 6.83 mg/g was obtained. The adsorption capacity of fly ash for anionic surfactant is higher as compared to the adsorption capacity of granite sand for anionic surfactant and fly ash for anionic dyes (reactive red 23 and reactive blue 171). Fly ash possesses capability to be used for the removal of anionic surfactants. © Published under licence by IOP Publishing Ltd.