Salicylic acid is a simple phenolic compound synthesized by many prokaryotic and eukaryotic organisms. In 1979, it was revealed that salicylic acid has a function in plant defense against various pathogens. The presence of the phytopathogenic fungus Ophiostoma novo-ulmi, which caused great damage in forest areas, causing the drying of elm trees, has been recorded in the territory of the Republic of Croatia. In this study, the electrochemical characterization of salicylic acid was performed and its influence on the growth of the phytopathogenic fungus O. novo-ulmi was investigated. The aim of the study was to determine the electrochemical properties of salicylic acid using electrochemical methods and to determine the influence of selected concentrations of salicylic acid on the growth rate of O. novo-ulmi isolates. Cyclic voltammetry confirmed the existence of an oxidation current peak related to the oxidation of the hydroxyl group of the phenolic ring of salicylic acid. Oxidation processes in the studied systems of alcoholic and aqueous salicylic acid solutions were proven to be under diffusion control and the oxidation current peak detected in aqueous salicylic acid solution was higher compared to the oxidation current peak of alcoholic salicylic acid solution. A linear dependence of the oxidation current peak on the salicylic acid concentration was obtained in the concentration range from 1,3 mM to 5 mM for the aqueous salicylic acid solution and in the concentration range from 1,3 mM to 2,5 mM for the alcoholic salicylic acid solution. Also, it was found that a 0,4 mM concentration of salicylic acid has an effect on the growth of some O. novo-ulmi isolates by stimulating their growth.