The present invention relates to a composition for use as an adhesive, paint, coating, resin, (surface) size, composite, gel or hydrogel, said composition comprising microfibrillated cellulose (“MFC”). In addition to microfibrillated cellulose, these compositions comprise at least one solvent, said solvent preferably comprising or consisting of water, and at least one compound that is (a) capable of polymerizing, or has already partly or fully, polymerized, and that (b) has at least two groups available for hydrogen bonding, preferably OH groups, that are capable of crosslinking with at least one functional group of the microfibrillated cellulose. In these compositions, the microfibrillated cellulose primarily functions as a crosslinking agent (while it is by no means excluded that the microfibrillated cellulose additionally has other functionalities, such as acting as viscosity modifier and/or thixotropic additive), integrating the compound that (a) is capable of polymerizing or that has already partly or fully, polymerized, and that (b) has at least two groups available for hydrogen bonding, into a gel-like three-dimensional network.