Micro-and Nano-Fibrillated Cellulose (MNFCs) have gained an increasing attention due to their remarkable properties, but their production usually requires an intensive multi-step process. This study proposes to find a novel approach involving steam explosion for the production of lignin-containing micro-and nano-fibrillated cellulose (L-MNFCs) using Eucalyptus globulus bark as a new lignocellulosic feedstock. Eucalyptus globulus bark was first pre-treated in alkali conditions by steam explosion in alkaline conditions (200°C, 8 min) or by soda cooking in a rotating autoclave (170°C, 60 min), refined and then grinded until the formation of gels. The chemical composition (Ionic chromatography, FTIR-ATR) of the pulps and morphology of the products (Morfi Neo, Optical and Atomic Force Microscopies (AFM), suspension turbidity) have been studied. Nanopapers were produced from lignin-containing microfibrils to investigate the mechanical properties. Results obtained showed that steam explosion produced pulps with slightly higher lignin content (≈ 9 %), containing shorter fibers (≈ 400 µm) and higher amounts of fine elements (≈ 86 %) compared to soda cooking (≈ 5 %, 2 ≈ 560 µm and 66 %, respectively). AFM images of SteamEx L-MNFC gels showed a web-like structure containing lignin nanoparticles.