The intercalation, at room temperature, of the sodium-potassium eutectic into graphite is performed, in a glove box under purified argon. It leads to a high alkali metal content powder. The annealing under vacuum, at 200°C for two days leads to a pure first stage compound whose formula is NaK2C12 with a color and a structure close to that of KC8. This phase is unstable and decomposes slowly in a mixture of KC8 and free alloy. However, this free alloy, which is liquid at room temperature, remains as inclusions between the graphene layers and the compound remains as a powder which can be useful for some applications when one needs large quantities of an alkali metal “solid” at room temperature, e.g. for gas purification (it reacts with oxygen and with moisture), for rapid and intense heat provider (it burns in air and the carbon is also participating to the heating), for ionic polymerization catalyst…