The redox potential of cobalt metal proves sufficient to oxidise the metal with a melt of imidazole. Depending on the temperature of the organic melt different three-dimensional cobalt imidazolate frameworks and hydrogen form. The initial product is [Co3(Im)6(ImH)2], which transforms under release of imidazole at 210 °C into [Co4(Im)8(ImH)]. The latter releases the remaining imidazole at temperatures >225 °C and forms homoleptic [Co(Im)2], which is thermally stable up to 550 °C. Thereby, a direct reaction route starting from the metal was established that prevents the use of toxic and sensitive metallocenes.