Abstract <p>Non-thermal plasma (NTP) enables non-equilibrium activation of CH₄ and CO₂ under mild conditions, offering an alternative route for low-temperature gas-to-liquid conversion. In this work, methane bi-reforming (CH₄/H₂O/CO₂ = 3 : 2 : 1) to methanol was investigated over Cu-based catalysts in a dielectric barrier discharge (DBD) reactor under three configurations: thermal catalysis (no plasma), in-plasma catalysis (IPC), and post-plasma catalysis (PPC). Experiments were conducted at atmospheric pressure with discharge power ranging from 30 to 60 W, corresponding to a specific energy input (SEI) of 15‒30 J/cm³. Discharge power was quantified using the Lissajous method. Among the tested configurations, IPC exhibited the best performance, achieving CH₄ and CO₂ conversions of 35 and 30%, respectively, a space-time yield of 3.6 mmol g^–1 h^–1, and an energy efficiency of 5.5% at SEI ≈ 22 J/cm³. In contrast, IPC showed higher conversion but lower stability and MeOH selectivity relative to PPC due to direct plasma-catalyst interaction. These results demonstrate that spatial separation of plasma and catalyst effectively enhances methanol selectivity and stability, providing design guidance for compact and decentralized plasma-assisted GTL processes.</p>