Composite compositions containing, as the major components, fine hydratable microfibril fibers obtained from cellulose or derivatives thereof and a solid capable of swelling with water, wherein at least part of the surface of the solid is coated with the fine microfibril fibers, and a process for producing the same. The solid capable of swelling with water is exemplified by particulate polymer absorbents to which short fibers have been added as the third component. These composite absorbents may be located on supporting sheets made of, for example, a nonwoven fabric to give composite absorbent sheets applicable to various absorbent products including diapers for infants and adults.