Abstract Azido-s-triazines containing –Cl, –OCH3, and –N(CH3)2 groups were synthesized, and their thermal reactions with some hydrocarbons were investigated with respect to the reaction products and the reaction kinetics. With non-olefinic hydrocarbons the reactions were found to proceed via a nitrene inteimediate; in the reactions with cyclohexane, cydohexylamino-s-triazines and amino-s-triazines were obtained. On the other hand, with olefinic hydrocarbons the reactions took place via a. bimolecular mechanism involving a formation of an intermediate of the triazoline type; in the reactions with cyclohexene, cyclohexenylamino-s-triazines were obtained along with amino-s-triazines; In both cases, the yields of alkylamino and alkenylamino-s-triazines increased with the electron-withdrawing power of the substituents in the s-triazine nucleus.