AbstractOptical absorption spectrum of Co2+ions doped in lithium sodium potassium sulphate single crystal has been studied at room and liquid nitrogen temperatures. The observed bands are assigned as transitions from the ground4T1g(F) to various excited quartet and doublet levels of Co2+ion in octahedral symmetry. The splitting in one of the bands at liquid nitrogen temperature has been explained as due to spin‐orbit interaction. All the observed band positions have been fitted with the parametersB,C,Dqand