Nowadays, the popularity of vanadium flow batteries is rapidly growing in the world due to higher stability during long-term operation and low costs when creating systems with long battery life. At the same time, research aimed at developing methods to increase the electrocatalytic activity of carbon felt materials in relation to vanadium ions has been largely developed to increase the specific power of flow cells, which are an integral part of vanadium flow batteries. One of the approaches to the modification of these materials is plasma treatment. In this work, two-stage plasma treatment of carbon felt was carried out, first in the medium of one gas, and then in the medium of another gas. Oxygen and nitrogen are selected as the gas. It has been shown that regardless of the order in which plasma treatment is performed, there is a similar trend in the value of the potential difference between the peak of oxidation and the peak of reduction, first it increases in the first stage, and then decreases in the second stage. However, nitrogen treatment at the second stage tends to decrease the potential difference more rapidly (almost 2 times), which we observe in this work.