Both the LiVO2 and NaVO2 play pivotal roles in the cathode materials of Li/Na ion batteries due to their high capacity and good stability. In this paper, the electronic structures and electrochemical properties of LiVO2 and NaVO2 are studied by the first-principles method. The delithiation/desodiation processes are calculated and the emphasis is put on the redox processes based on the analysis of the calculated Bader charges. Results show that both the V and O ions participate in the redox reaction processes, with V ions lose much more electrons than O ions. Electronic structures, such as the electronic density of states, V–O bonding characters during the delithiation/desodiation processes are employed to comparatively study the redox processes in LiVO2 and NaVO2. The magnetism of Li1-xVO2 and Na1-xVO2 during the delithiation/desodiation processes are elucidated by the Stoner criterion.