Microporous polymer frameworks have attracted considerable attentiont om ake novel separation layers owing to their highly porouss tructure, highp ermeability,a nd excellent molecular separation. Thiss tudy concernst he fabrication and properties of thin melamine-based microporous polymer networks with al ayer thickness of around 400 nm, supported on an a-alumina support and their potentialu se in organic solvent nanofiltration. The modifiedm embranes show excellent solventp urificationp erformances, such as n-heptane permeability as high as 9.2 Lm À2 h À1 bar À1 in combination with avery high rejection of approximately 99 %for organic dyes with molecular weighto f! 457 Da. These values are higher than for the majority of the state-of-the-artm embranes. The membranesf urther exhibit outstanding long-term operation stability.T his work significantly expands the possibilities of using ceramic membranes in organic solventn anofiltration.Supporting Information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.org/10.