Perdeuterated compounds, 4-benzylideneamino-TEMPO-d23, 4–(p-chlorobenzylideneamino)-TEMPO-d22, and 4-hydroxyimino-TEMPO-d17(TEMPO = 2,2,6,6-tetramethylpiperidin-1-yloxyl) were synthesized and their magnetic properties were studied. The magnetic measurements down to 1.8 K did not show significant difference by the replacement of hydrogens with deuteriums. The temperature of the ferromagnetic phase transition of 4-hydroxyimino-TEMPO did not change by deuterium substitution.