Green Expo, Belgium’s largest sustainable-development trade fair, returns in a fully in-person format to the Mons-Expo convention centre on 18-19 September 2025. Organised by the Walloon environmental agency and the Province of Hainaut, the two-day event expects 8 000 visitors and 300 exhibitors spread across 15 000 m² of indoor and outdoor space. The programme is built around six parallel thematic valleys: circular economy, energy transition & storage, sustainable construction & renovation, low-carbon mobility, water & biodiversity management, and sustainable agriculture & food systems. Each valley combines demonstration zones, product showcases, policy round-tables and technical workshops so that public authorities, corporate managers, installers, architects, farmers and citizens can all find actionable solutions. A 2025 spotlight is the new “Climate Tech Start-up Village” where 40 early-stage companies pitch innovations ranging from bio-based insulation to AI-driven energy monitoring. The Walloon Minister for Climate, the Brussels-Capital Secretary of State for Economic Transition and the European Investment Bank’s vice-president have already confirmed they will deliver keynote addresses on the main stage, while the European Commission’s DG Climate Action will present the latest funding calls under LIFE and Horizon Europe. Parallel sessions include a half-day masterclass on the EU Carbon Border Adjustment Mechanism, a safety-training zone for electricians installing domestic batteries, and a farmers’ clinic on agro-ecological certification. Admission is free after online registration, and the site is served by extra trains from Brussels and Lille on both days. Visitors arriving by bicycle or e-vehicle receive priority parking and a voucher for the organic food court. Green Expo is certified by the A Greener Festival alliance: all catering is vegetarian by default, badges are printed on seed paper, and the power demand of the site is covered 100 % by renewable energy contracted through the local cooperative.