Np-237 Mossbauer spectrum of the heptavalent neptunium compound [Co(NH3)6][
NpO4-(OH)(2)]. 2H(2)O was remeasured for certification of the previous inve
stigations. The isomer shift value of the Mossbauer spectrum showed a chara
cteristic value for the heptavalent neptunium at 4.7 K. Although the spectr
um seemed to consist of two quadrupole-split peaks as previously reported b
y STONE et al., the fitting with using two quadrupoles-split peaks did not
give a good agreement with STONE'S data.