Using density-functional-based methods, we show that the hole-doped Li x BC and Na x BC in P6 3 /mmc crystal structure and C x in graphite structure are capable of showing superconductivity, possibly with a T c much higher than that of MgB 2 . We use the pseudopotential method to obtain the optimized lattice constants a and c, the coherent-potential approximation to describe the effects of disorder, the Gaspari-Gyorffy formalism to obtain the electron-phonon coupling constant λ, and the Allen-Dynes equation to calculate T c as a function of hole concentration in these alloys.