In an air supplier particularly for air supply systems for fuel cells including a compressor having a housing with a radial diffuser and including a rotor operated by an electric motor, a diverting channel is connected to the radial diffuser providing a communication path guiding the air via an axial annular channel to an inwardly extending collecting chamber via a final diffuser formed by a curved end section of a wall delimiting the annular passage and an inwardly curved wall area of the collection chamber, the compressor housing having an outer diameter is not substantially larger than the outer diameter of the electric motor.