Abstract <p>The possibility of using the new antioxidant “Carboxychromanate 2-ethyl-6-methyl-3-hydroxypyridine” (Ch-3HP) to improve plant resistance to stress was investigated. The studies were conducted on the mitochondria of etiolated pea (<i>Pisum sativum</i> L.) seedlings, using water deficiency as a stress model. A 2.4-fold water deficiency activated lipid peroxidation in the membranes of seedling mitochondria. In this case, the double bond index of C₁₈ fatty acids (FA) decreased from 1.33 ± 0.01 to 1.25 ± 0.01, and the double bond index of C₂₀ FA dropped by 45%. Under these conditions, the activity of complex I of the mitochondrial respiratory chain decreased by 29%. Ch-3HP at concentrations of 10^–6 M and 10^–9 M prevented changes in the bioenergetic characteristics of mitochondria. Furthermore, treatment of pea seeds with the preparation prevented activation lipid peroxidation and changes in the FA composition of mitochondrial membranes. The preparation prevented a decrease in seedling growth rates under stressful conditions. Furthermore, application of Ch-3HP to wheat (<i>Triticum aestivum</i> L.) seedlings had a growth-stimulating effect. The preparation can be used as a plant growth regulator.</p>