A new mechanism of formation of nanopores in carbon materials is suggested. According to this mechanism, the formation of carbon from carbides under certain conditions is accompanied by the self-organization of reaction products. The restructuring of the carbon crystal lattice then occurs with a certain period in space determined by the kinetics of the carbon synthesis reaction, which initiates the generation of vacancies, also periodic in space. In a certain time interval, the gas of vacancies becomes supersaturated, and the nucleation of pores begins and eventually results in a porous carbon structure. The intensity of space-periodic vacancy generation substantially depends on the time of chlorine action on crystalline carbide grains. This dependence is universal in character and has three maxima. The nucleation of pores occurs at the instants of time corresponding to these maxima. The optimal size of pores of the best structure was estimated at 5 × 10^-4 m.