The objective of the current work is the exhaustive study of the phenol degradation potential in both free cell and immobilized bacterium (Pseudomonas aeruginosa) in calcium alginate beads (biocatalyst) was investigated for its ability to grow and degrade phenol as its sole source of carbon and energy. The biodegradation assays were performed in liquid medium with phenol being the only substrate. It was found that P. aeruginosa is able to degrade phenol up to 500 mg L^(-1) in 50 h as free cell and 900 mg L^(-1) in 80 h when immobilized in the calcium alginate beads. However, for 1200 mg L 1 concentration, the immobilized cells took much more time (290 h) for a complete degradation. The reuse of these beads in different concentrations of phenol (100-900 mg L^(-1)) showed that the cells keep their phenol degradation ability up to 900 mg L^(-1)in 78.5 h with 99% removal efficiency. Similarly, the reuse of the biocatalyst in the same initial phenol concentration (500 mg L^(-1)), allows us to get 9 cycles.