A new nitronyl nitroxide bridged one-dimensional lanthanide complex [Tb(3)(hfac)(9)(NIT-2thien)(3)](n) (1) (NIT-2thien = 2-(2'-thienyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) has been successfully prepared. Single crystal X-ray crystallographic analysis reveals that complex 1 consists of linear chains built up by Tb(hfac)(3) units bridged by NIT-2thien radicals through their NO groups; the chains run along the crystallographic a-axis. The magnetic behavior of complex 1 is quite unusual. The complex shows the concomitant existence of slow magnetic relaxation and three-dimensional magnetic ordering.