Reductive depolymerization of lignin-containing stillage (LA lignin) from 2nd generation bioethanol industrial plants have been studied over two different families of catalysts: conventional porous Ru catalysts supported on ZrO2 or activated carbon, and 1-dimensional Ru catalysts supported on multi-walled carbon nanotubes (MWCNT). The lignin depolymerization degree using conventional porous catalysts resulted in values of 42 and 53%, for Ru/ZrO2 and Ru/C, respectively. Strikingly, when using 1D-supported catalysts (Ru/MWCNT and Ru/ZrO2/MWCNT), the extent of lignin depolymerization measured by 1H13C HSQC NMR, reached values of c.a. 80% of β-O-4 bond disappearance and a reduction of the average molecular weight from 3600 Da to ~ 1900 Da. The higher accessibility of the lignin agglomerates to the 1-D catalyst nanoparticles substantially improves the lignin depolymerization degree, which make this approach of great interest in the production of fine chemicals and fuel additives. Display omitted •Lignin stillage has been depolymerized up to 80% of β-O-4 bond disappearance.•Selective depolymerization of β-O-4 ether bonds has been achieved on Ru catalysts.•1-D Ru/MWCNT catalysts show the highest depolymerization extent.•1-D Ru/MWCNT catalysts increase accessibility of the lignin molecules to the catalyst.