  We discuss threshold resummation in radiative and charmless semileptonic B
decays. To deal with the large non perturbative effects, we introduce a model
for NNLL resummed form factors based on the analytic QCD coupling. By means of
this model we can reproduce with good accuracy the experimental data. Finally
we briefly present an improved threshold resummed formula to deal with jets
initiated by massive quarks as in the case of semileptonic charmed decays.
