Thermal decomposition of the most common plastics such as polyethylene and polypropylene produces a mixture of many different hydrocarbons that can be used as a feedstock for producing hydrogen. The proposed process includes two steps: pyrolysis of plastics and catalytic steam reforming of pyrolysis gases and vapors. This research provides a proof of concept supported by experiments on selected polymers performed using a microscale reactor system interfaced with a molecular beam mass spectrometer and demonstrates process performance using a two-reactor bench-scale system. From 60 g/h polypropylene fed to the system 20.5 g/h hydrogen was produced, which corresponds to 80% of the theoretical potential.