B ->pi and B -> K transitions from QCD sum rules on the light-cone

I calculate the form factors describing semileptonic and penguin-induced de cays of B mesons into light pseudoscalar mesons. The form factors are calcu lated from QCD sum rules on the light-cone including contributions up to tw ist 4, radiative corrections to the leading twist contribution and SU(3)-br eaking effects. The theoretical uncertainty is estimated to be similar to 2 0%. The heavy-quark-limit relations between semileptonic and penguin form f actors are found to be valid in the full accessible range of momentum trans fer.