Laser flash photolysis was applied to study the photochemistry of PtBr 6 2− complex in aqueous solutions with the presence of free Br − anions. Laser pulse is followed by the formation of Br 2 •− radical anion, which reacts with the initial complex with the rate constant k=9×10 8 M −1 s −1 yielding the complex of Pt(V). Analysis of Br 2 •− quantum yield via bromide concentration testifies that a bromine atom is formed by an electron transfer from a free Br − anion to the light-excited complex. PtBr 6 2− photoaquation occurs via heterolytic cleavage of the Pt–Br bond. Addition of free bromide anions sufficiently decreases the quantum yield of photoaquation.