Elastic recoil detection analysis (ERDA) has been developed for determining the amount of hydrogen-atoms in a film. The principle and some preliminary results of the method are given in this paper. The hydrogen content in a VYNS thin film was measured and found to be in agreement with the PIXE analysis within ±10%. This method is suitable for thin films of thickness of 1~10μm with sensitivity being about 5 × 10

15

at./cm

2

.