The 14N(p, γ)15O reaction has been investigated by LUNA at the National Laboratory of Gran Sasso (LNGS) using two different techniques. The first study has been performed using a solid target and detecting the γ-rays coming from the single transitions with a HPGe detector in very close geometry to the target. In a second phase a windowless gas target sorrounded by a nearly 4π BGO summing crystal has been used and the total S-factor has been measured down to Eb = 80 keV. © 2005 Elsevier B.V. All rights reserved.