Solvation of lithium ions in the organic electrolyte solutions for primary lithium batteries was investigated by electrospray ionization-mass spectroscopy (ESI-MS). In LiBF4/γ-butyrolactone (GBL), lithium ions were solvated to GBL molecules in the form [Li(GBL)2]+ or [Li(GBL)3]+, and in LiClO4/ dimethoxyethane (DME)–propylene carbonate (PC), lithium ions were solvated mainly to DME and PC in the form [Li(DME)(PC)]+.