Résumé : The 19Ne(p,γ)20Na as well as the 19Ne(d,n)20Na reaction have been studied in inverse kinematics using 19Ne radioactive beams. Upper and lower limits for the 19Ne(p,γ)20Na astrophysical reaction rate have been deduced, for the first time on the basis of direct experimental data. It is concluded that the transition from the hot-CNO cycle to the rp-process in explosive hydrogen burning is most likely governed by the preceeding 15O(a,γ)19Ne reaction.