Intermetallic Fe-Al type coatings were deposited in air on plain carbon steel substrate by Detonation Gas Spraying (DGS). The adhesion strength was tested by three-point bend test combined with acoustic emission (AE) and metallography. On the basis of processing of AE signals, the damage source in the investigated coatings was identified and localized into SEM and optical microscopy. The suggested delamination mechanism is the initial formation of a radial crack in the DGS intermetallic Fe-Al type coating after which the de-lamination process occurs. The results show that the beginning of delamination of DGS intermetallic coatings with typical splash structure is shifted with respect to the moment of radial crack initiation. Acoustic emission technology has been combined with three-point bending test and metallography to characterize DGS intermetallic coatings properties and has been applied to better understand failure mechanisms and to predict lifetimes.