We used quantum-chemical methods to study seven possible mechanisms of monoamine oxidase (MAO) inhibition by acetylenic inhibitors, considering neutral, cationic, and anionic forms of the inhibitors. Our results show that the inhibition of MAO by acetylenic inhibitors is a complex process involving multiple steps and interactions between the inhibitor and the enzyme. The study provides new insights into the mechanisms of MAO inhibition and may lead to the development of new therapeutic agents for the treatment of neurological disorders.