To overcome these challenges, novel materials have been proposed for advanced humidity sensing, such as supramolecular nanoassemblies, polymer/metal nanoparticle hybrids, 5 2D materials, e.g., MXenes, or carbon-based materials like graphene oxide (GO), or reduced GO (rGO). GO-based materials are attractive candidates for detecting humidity due to GO's high hydrophilicity, large surface area, and flexibility. While the GO surface is decorated with numerous polar functional groups that can serve as sorption sites for water molecules, this functionalized active surface includes sp 3 hybridzation of the lattice atoms, limiting the applicability of GO as a resistive sensor due to its insulating character. However, several reduction methods can be applied to restore the sp 2 carbon system, resulting in rGO with increased conductivity, but with reduced sensitivity towards humidity, caused by the removal of the oxygen-containing functional groups. Numerous studies explored the potential of rGObased materials for resistive humidity sensing, also addressing notions to reconcile these two counteracting effects for optimized sensing performance. Recently, Samorì and colleagues demonstrated that chemically introducing hydrophilic motifs onto rGO enhances the resistive response towards humidity compared to pristine rGO sheets. Further, the combination of rGO with other nanomaterials can lead to synergistic effects and enhanced humidity sensing characteristics. For instance, recent works proposed hybrid layered films of rGO/silk fibroin, rGO/polymer layers, or rGO/Fe 2 O 3 nanoparticle films, among numerous others, as flexible, resistive sensors for the potential detection of physiological humidity.