A novel molecular magnetic material with the formula of {[Mn2(salen)2(C4H3SSeO2)](ClO4)}n (Complex 1) [salen = N,N′-(ethylene)bis(salicylideneiminato)] was designed, synthesized and characterized structurally and magnetically. This complex crystallizes in the triclinic space group Pī and exhibits a one-dimensional (1D) zig-zag chain structure, which is formed through linking Mn2(salen)2 dimers by O–Se–O in syn–syn coordination mode. All the Mn(III) atoms in the chain display a six-coordinate distorted octahedral geometry. It is revealed by static magnetic measurement that there is antiferromagnetic coupling between the Mn(III) ions through selenite ligands (O–Se–O), while ferromagnetic coupling through a double phenoxido bridge of the MnIII dimer. Due to the strong uniaxial anisotropy of Mn(salen), complex 1 behaves as the single chain magnet (SCM)-based antiferromagnet. This compound represents a rare example of an O–Se–O bridged Mn(III)-based system with the SCM dynamics. [ABSTRACT FROM AUTHOR]