Carbon materials (A-1, A-2 and A-3 derived from pitch cokes) with different graphitization degree, were allowed to react with potassium. The hydrogen-sorption behavior at 77 K, electrical resistivity. ESR and Raman spectra of the resulting compounds with the composition of KC60were determined. The sorbed amount at saturation, (nH2/nK)sat, was 0.55 and 1.43 for KC60s prepared from A2 (d002= 0.3377 nm) and A3 (d002= 0.3361 nm), respectively. No H2sorption was observed for KC60from A-1 (d002=0.342 nm). Temperature dependence of the resistivity of KC60s from A-2 and A-3 showed metallic behavior, contrary to semiconductive one for the host materials. However, KC60(A-1) showed semiconductive temperature dependence, similarily to the host material. Raman spectra of KC60s from A-2 and A-3 showed doublet structure, similarly to that of K-GICs from HOPG, characteristic for graphite intercalation compounds with stage n > 2. On the contrary, KC60(A-1) gave single peak at around 1597 cm−1. Those facts suggest that potassium exists in the interlayer spaces for KC60s (A-2, A-3), but not for KC60(A-1). It was also shown that g-factor of ESR spectra of KC60can be useful to predicting the H2-sorption behavior.