A novel chiral organic radical 2-{4'-((S)-2 "-methylbutoxy)phenyl}-4,4,5,5-tetramethylimidazoline-1 -oxyl-3-oxide (1) and its metal complex, [1 . Mn(II)(hfac)(2)](n) were synthesized and characterized. The radical 1 crystallizes in the orthorhombic space group P2(1)2(1)2(1) (No.19) with a = 11.494(3) Angstrom, b = 25.328(3) Angstrom, c = 6.1281(5) Angstrom, V = 1748.0(4) Angstrom(3). The complex [1 . Mn(II)(hfac)(2)](n) crystallizes in the same space group with a = 14.081(1) Angstrom. b = 15.940(1) Angstrom, c = 16.075(1) Angstrom, V = 3608.1(4) Angstrom(3). X-ray crystal structure analysis of the complex revealed the formation of a helical-chain structure. The oxygen atoms of the radical 1 are ligated to two different manganese ions in cis position and exhibit the Delta configuration in [1 . Mn(II)(hfac)(2)](n). The magnetic measurements revealed that this chiral complex behaves as a ferrimagnet below T-C = 4.5 K. It is characterized by a strong intrachain exchange correlation. the ratio between the intrachain and interchain exchange interactions being about 10(-5).