Biosorption is an effective technique for  removing  heavy metals from the aquatic environment. The aim of this study was to assess the potential of microalgae species Chlorosarcinopsis eremi in immobilized and free biomass state for nickel removal. Removal efficiency was studied at pH 7± 2, temperature of 25C ̊ , initial metal concentrations of 5, 10 and 15ppm, contact time ranging from 0– 8 days, and agitation speed of 120rpm.  The highest removal percentages for all coefficients (immobilized biomass, free biomass, and blank alginate beads) were recorded at a concentration of 5 ppm, with values of 62.74, 49.54, and 38.86%, respectively. While, the lowest percentage of removal was associated with concentration of 15ppm for all coefficients, as it reached 50.27, 35.04, and 24.30%, respectively. The relationship was positive between the percentage of removal and increased exposure to the metal ions and reached its maximum on the sixth and eighth days of the experiment, for all coefficients and concentrations. While  the highest removal percentage of blank alginate beads was recorded at the second and fourth days of the experiment.  Biosorption was analyzed using Langmuir and Freundlich isotherms. Additionally, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analyses conducted before and after biosorption revealed that nickel ions were primarily adsorbed onto the surface of the algae cells during the biosorption process.