A composite structure mainly composed of hydratable fine fibers in the form of microfibril and a water swellable solid body, the fibers being obtained from cellulose or derivatives thereof, and at least part of the surface of the solid body is covered with the fine fibers. The absorbent composite can be formed in various form of, for example, particle, pellet, sheet and the like, especially of a sheet type with a supporting sheet of a non-woven fabric. The present invention further provides a method of making the composite structure.