The reaction of N-alkyl(aryl)-1,2(1,3)-diaminoalkanes with formaldehyde and alcohols is accompanied by condensation-heterocyclization of corresponding 1,2(1,3)-diaminoalkanes with formation of 1-alkylhydroxymethyl-3-alkyl(aryl)-1,3-diazacycloalkanes. The obtained compounds are effective aminomethylating (alkylating) agents, which opens up opportunities for synthesis of new derivatives of 1,3-diazacycloalkanes. Microbiological tests have shown high antimicrobial activity of these compounds with respect to microorganisms that degrade oil products. The antimicrobial activity has been found to depend on the nature of the nitrogen-substituent and the number of carbon atoms in the hetrocycle.