The electrochemical synthesis of ternary graphite intercalation compounds (GICs) with ferric chloride and an organic solvent is described. Stage IV and V ternary GICs with identity periods I c = 19.19 Å ( d i = 9.14 Å) and 22.70 Å ( d i = 9.30 Å), respectively, are obtained in solutions of FeCl 3 in acetyl chloride. In the graphite-FeCl 3 -CH 3 COOH-HCl system, a ternary GIC with a transition-metal chloride (FeCl 3 ) and weak aprotic acid (CH 3 COOH) (stage III, I c = 16.15 Å, d i = 9.45 Å) is synthesized for the first time. Using radiotracer analysis, the solvent molecules are shown to be evenly distributed over the graphite host. Thermal analysis results demonstrate that GICs with FeCl 3 and ternary GICs with FeCl 3 and acetic acid differ markedly in thermal properties. The synthesized GICs offer record large expansion on flash heating. The resulting exfoliated graphite contains residual Fe 2 O 3 .