The corrosion and electrochemical behavior of magnesium and the MA 21 magnesium-lithium alloys in solutions of moderately acidic phosphates with various additives was studied. The inhibiting effect of nitrate and fluoride ions on the anode dissolution of these objects was revealed. Features of the electrochemical dissolution of magnesium and the magnesium-lithium alloys in nitrate phosphate solutions with fluoride ions caused by their activation-passivation competition have been noted. Distinctive features of the electrochemical behavior of the magnesium-lithium alloys in comparison with pure magnesium in nitrate phosphate fluoride solutions due to their structural and phase specifics have been established.