Hydrogen plasma-driven permeation (PDP) experiments have been conducted, using a steady state linear plasma device for the membranes made of reduced activation ferritic steel (F82H) and stainless steel (SUS304). The steady state PDP ratios have been measured to be of the orders of 10-3 and 10-4 at ~220 °C for 1 mm thick F82H and SUS304 membranes, respectively. For F82H, the steady state PDP flux ratio has been found to be inversely proportional to membrane thickness at ~220 °C, indicating that permeation is diffusion-limited. From the temperature dependent PDP data for F82H an activation energy has been evaluated to be ~0.5 eV.