A cellulose formate fiber of liquid-crystal origin, having a high elongation at break and having the following characteristics:a) under an optical polarizing microscope, its filaments have a banded structure typical of its liquid-crystal origin;b) it satisfies the following relationships:DS.gtoreq.2; Ar.gtoreq.8; Te 500; Er>10,DS being the degree of substitution of the cellulose with formate groups in the fiber (in %), Ar the elongation at break (in %) of the fiber, Te its tenacity (in cN/tex), Mi its initial modulus (in cN/tex) and Er its energy at break (in J/g).Also, a process for obtaining this cellulose formate fiber by "dry-jet-wet-spinning" of a liquid-crystal solution of cellulose formate, in which water is used as coagulating agent. A fiber of cellulose regenerated from cellulose formate which itself has a high value of elongation at break, and a process for obtaining this fiber.