ABSTRACTDepth profiling of hydrogen in polymeric materials poses special problems. Backscattering methods are ruled out because of kinematics. Nuclear reaction methods are undesirable because small reaction cross sections necessitate large fluences of high mass projectiles and result in unacceptable levels of radiation damage. We have used a helium-induced proton-recoil technique with 3 MeV ⁴He particles to measure the hydrogen distribution in pristine and ion-implanted polyvinylidene fluoride (PVDF) films. The incident ⁴He particles stopped in the 25 micron PVDF films while the recoiling protons were detected after passing through the polymer film. Large changes in the hydrogen content of PVDF films implanted with modest fluences of 6 MeV carbon, oxygen and nickel ions were observed.