A hemiquantal three-dimensional calculation of the isotopic exchange reaction O-18(P-3) +(OO16)-O-16((3) Sigma(g)(-))-->(OO16)-O-18((3) Sigma(g)(-))+O-16(P-3), which plays an important part in the atmospheric ozone photochemistry, is presented. The method gives an estimation of the lifetime of the activated complex which may be formed during the collision. Reaction scattering cross sections and rate constants are determined. A comparison with previous classical calculations and experimental results are made.