Abstract The structures and magnetic properties of Co(6)/Mn( t Mn) multilayers were systematically investigated by X-ray diffractometry and SQUID magnetometry to reveal the effects of interfacial d–d hybridization on them. Increasing Mn layer thickness, the main profile in HAXRD patterns changes from a single peak for t Mn⩽7 Å to split peaks for t Mn⩾10 Å. With decreasing the temperature, the magnetization increases greatly through two magnetic transitions at the temperatures much lower than that of bulk α-Mn. At 5 K, the absolute value for the magnetization becomes unusually large. The magnetization is highly anisotropic and for t Mn⩽20 Å, the perpendicular direction is the easy magnetization axis. Correlations between the magnetization, exchange bias and coercive force are found. The high magnetization and the correlations are interpreted in terms of the direct d–d hybridization in the vicinity of Co–Mn interfaces.