© 2019 South African Association of BotanistsThe increased applications of synthetic dyes in the textile industrial activities have negative implications such as water pollution by dye containing effluents. The treatment of industrial wastewater is important due to the toxic effects of dyes. Biosorption is defined as a relatively economical and eco-friendly wastewater treatment method. The aim of this study was to examine the biosorption of Acid Red P-2BX (ARP-2BX) dye that is extensively used and abundantly found in textile wastewater. The dye biosorption capacities of prokaryotic algae (Phormidium animale) and eukaryotic algae (Scenedesmus sp.) were investigated. The effects of pH (2–10), biosorbent type (ash or dried), initial dye concentration, biosorbent dosage, contact time and temperature were determined. Maximum dye removal was performed by dried P. animale as 99.70 ± 0.27%. The biosorption isotherms and kinetics were also calculated, the ARP-2BX dye biosorption was fitted with Langmuir isotherm and pseudo-second-order kinetic models. In order to analyze the changes that occurred in algal structure, FTIR and elemental analysis were done. The results of this study concluded that P. animale was a favorable biosorbent for treatment of textile wastewater.