Butyl- and hexyloctamethylferrocenium salts with bis(trifluoromethylsulfonyl)amide (TFSA) and tetracyanoethylene (TCNE) were prepared, and their thermal properties were investigated by differential scanning calorimetry (DSC) measurements. The TFSA salts were ionic liquids with melting points of 34.4 degrees C and 27.7 degrees C, respectively. The TCNE salts were prepared by annealing the mixture of alkyloctamethylferrocene and TCNE. These salts exhibited high melting points of 100.2 degrees C and 80.9 degrees C, respectively; they were thermally unstable at higher temperatures. A butyloctamethylferrocenium salt with PCNP (pentacyanopropenide), obtained by a reaction with TCNE under ambient conditions, was crystallographically characterized. The structure was severely disordered, consisting of alternately stacked cations and anions. (C) 2011 Elsevier B.V. All rights reserved.