There is disclosed a centrifugal compressor including an impeller rotatable about an axis and a diffuser downstream of the impeller. The diffuser has walls delimiting flow passages. Plasma actuators are positioned adjacent the walls and are operatively connectable to a source of electricity. The plasma actuators have a first electrode, a second electrode, and a dielectric layer therebetween. The first electrode is upstream of the second electrode. The first electrode is exposed to the flow passage. The second electrode is shielded from the flow passage by the dielectric layer. The plasma actuators are operable to generate an electric field through the dielectric layer. The plasma actuators are located closer to inlets of the flow passage than to outlets of the flow passages. A method of operating the compressor is disclosed.