The optical absorption studies on cobalt doped binary lithium phosphate glasses yLi2O-(100-y)P2O5 reveal a mixed octahedral and tetrahedral coordination for the cation sites through the characteristic bands 4T1 (F) → 4T1 (P) at ∼530 nm and 4A2 (F) → 4T1 (P) at ∼580 nm. The glasses show an increase in the number of tetrahedral sites as the modifier concentration increases which may be attributed to the increased optical basicity of the glasses. An enhancement in the ionic conductivity with increase in the dopant (Co2+) concentration is observed in the glasses which may be due to Co2+ entering Li+ sites resulting in the generation of cation vacancies.