A number of aminomethylated derivatives of 2-propenyl-, 4-isopropenylphenols have been synthesized and their antimicrobial properties have been studied in M-12 engine oil and TS-1 jet fuel (at concentrations of 1-2% and 0.3-0.5%, respectively). They have been found to possess bactericidal and fungicidal properties and significantly improve the antimicrobial properties of both of the materials (as compared to the well-known antimicrobial additive, 8-hydroxyquinoline). The presence of an alkenyl substituent along with an aminomethyl group in the structure of the substances in question has been demonstrated to enhance the antimicrobial properties. The formation of an intermolecular and intramolecular hydrogen bond in the initial and synthesized phenolic compounds has been studied.