As part of the GreenRAIM activity of the European Space Agency (ESA), an extensive test campaign involving various monopropellants was undertaken. In this work, design and test results of an additively manufactured 1-Newton monopropellant thruster are shown. The detailed design of the thruster and the experimental setup are presented. The first part of the test campaign was conducted with 98 wt.% hydrogen peroxide as the propellant and a commercially available Pt/Al₂O₃ catalyst. The second part was carried out with the same thruster but using nitrous oxide as the propellant and an iridium-based catalyst. The test data acquired was used to validate a comprehensive, generic model for monopropellant thrusters within the simulation software EcosimPro/ESPSS v3.7, which was developed within the activity.