Visible absorption spectra of the radical Solutions of diphenyl, phenantrene, chry- sene and a-a'dipyridyl, prepared in THF solvent by using Na, have been taken and ab­ sorption minima of the first three of the Solutions were found to be located at 481, 538, 560 m|x respectively.Meantime it was found that absorption minimum of the dipyridyl is shifted to the near IR.The graphs, representing the extinction coefficients of the radical Solutions as function of the radical concentrations have been drown. These curves can be used to determine the unknown concentration of the radical by the spectrophotometri- rical method.