The OPERANDUM training materials aim to emphasize the knowledge generated through the EU-funded OPERANDUM project and promote the uptake of Nature-based Solutions for hydro-meteorological hazards in Europe and beyond. Embedded in a series of training units, the materials address common knowledge gaps and highlight lessons learned from the NBS co-creation process at OPERANDUM Open-Air Laboratories across Europe. The training series is made publicly available for diverse learning purposes and educational contexts.