Adamantanes and diamantanes, whose abiogenic synthesis from carbon and hydrogen is feasible, were synthesized via the high-temperature cracking of individual n-alkanes in order to reveal the possible ways of the genesis of hydrocarbons with a diamond-like structure. As a result of the high-temperature cracking of n-alkanes, all theoretically possible isomers of C(10)-C(13) adamantanes and C(14)-C(16) diamantanes are formed, as well as n-alkanes up to C(35)H(72) and coke.