The study aimed to investigate the efficiency of exogenous bacterial consortium (Enterobacter cloacae and Pseudomonas otitidis) decorated (immobilized) with Fe 3 O 4 Nanoparticles for the treatment of petroleum hydrocarbon-contaminated wastewater. Glycine coated magnetite Nanoparticles (Fe 3 O 4 NPs) were prepared using reverse co-precipitation method and were characterized using X-ray diffraction, transmission and scanning electron microscopy and vibrating sample magnetometer. They were used to decorate exogenous bacterial consortium (Enterobacter cloacae and Pseudomonas otitidis) at 3 different Fe 3 O 4 /bacteria ratios (1:1, 1:3 and 3:1 w/w). Bioremediation of oil contaminated wastewater collected from one of the petroleum distribution companies, Alexandria was conducted for 168 h using Fe 3 O 4 /bacterial association at the best ratio (3:1) and compared with non-decorated consortium and the indigenous bacteria in the control. Analysis indicated crystalline structure of Fe 3 O 4 NPs with spherical particles (size: 15-20 nm) and superparamagnetic properties. Glycine modified-Fe 3 O 4 exhibited high ability to immobilize bacteria which acquired its magnetic properties. The highest coating efficiency (92%) was achieved at 3:1 Fe 3 O 4 /bacteria ratio after 1 h. This ratio positively affected bacterial growth reaching the highest growth rate (5.07 fold higher than the control) after 4 h. The highest removal efficiencies of the total suspended solids (TSS), chemical oxygen demands (COD), oil and grease (O&G) and total petroleum hydrocarbons (TPH) recording 96, 65.4, 83.9 and 85% reaching residual concentrations of 9.5, 598, 99 and 60 mg/l respectively were achieved after 4 h by the Fe 3 O 4-bacteria assembly. Compared with the maximum permissible limits of the tested parameters, TSS residue was highly compiled with its limit (50 mg/l), while COD, O&G and TPH were 7.5, 9.9, and 120-folds higher than their limits (100, 15 and 0.5 mg/l respectively). To the best of our knowledge it is first time to use integrated Enterobacter cloacae and Pseudomonas otitidis consortium decorated with Fe 3 O 4 NPs for the treatment of petroleum hydrocarbon-contaminated wastewater. The proposed system proved to be a very efficient, economical and applicable for the removal of the included contaminants in very short running time which increases its biotechnological added value.