The polymeric coordination compound of formula [Tm(hfac) 3 (NITPhOPh)] ∞ (where NITPhOPh is a nitronyl-nitroxide radical) has been synthesized and found to belong to the only reported family of isostructural Single Chain Magnets. Both static and dynamic magnetic measurements have been performed, and a dependence of the out-of-phase signal on the frequency is observed below 3K. Scaling procedures indicate Ising magnetic anisotropy. Comparison of the extracted parameters with those of the previously reported isostructural compounds confirms a trend along the lanthanide series.