A low-cost inorganic acid-activated clay was used as adsorbent for the adsorption of six dyes (two basic, one acidic, one disperse, one direct dye, and one reactive) from aqueous solutions. The adsorption capacity was comparatively high for basic dyes and was lower for disperse, direct, and reactive dyes. The equilibrium data could be well described by the Langmuir equation over the entire range of concentration (50∼500 mg dm−3). In addition, the effect of temperature on the adsorption was examined and the thermodynamic data were determined. Based on the adsorption capacity only, it was generally shown that activated clay was more effective compared to other commonly used adsorbents.