The settling velocity of flocculated materials is one of the most important factors for the appropriate design and the effective operation of wastewater treatment plants. In this study, the effect of some variables, such as settling temperature and pH, concentrations of a cationic surfactant and an electrolyte on the settling velocity of aluminium hydroxide-dye flocs have been investigated. The aluminium hydroxide was produced by dissolving metallic aluminium under high temperature in alkaline medium. The dyestuff chosen for this study is a reactive textile dye, Remazol Red RB. Cationic surfactant (CTAB) and electrolyte (NaCl) were used as settling aids. The experimental results showed that the settling velocity generally increased with the increasing settling temperature, pH and dye concentration. By using the experimental data related to the temperature an empirical equation was developed and the Ea values for the settling process of the flocs with dye and without dye were determined as 20.40 kJ, and 14.17 kJ, respectively.