Abstract The static magnetic susceptibilities of poly crystalline samples of 1,1-bis(p-chlorophenyl)-2-picrylhydrazyl (Cl-DPPH), 1,1-bis(p-bromophenyl)-2-picrylhydrazyl (Br-DPPH), and 1,1-bis (p-methoxyphenyl)-2-picrylhydrazyl (CH3O-DPPH) were measured in the temperature range from 10°K to 300°K. These three substances showed strong paramagnetism comparable to that of DPPH, having relatively weak interaction energies between their unpaired electrons. Of these, the paramagnetic susceptibility of CH3O-DPPH was analysed on the basis of the singlet-triplet model with the energy separation of 2J/k=33.8°K.