An advantageous and effective process for obtaining carboxymethyl cellulose (CMC) from agro-industrial residues, comprising the steps of a) Preparing the raw material, wherein the raw material is washed, dried, grounded and washed again; b) a pumping step, wherein the product obtained from the step a) is reacted with sodium hydroxide; c) a synthesis step, wherein consists in grounding the pulp; adding a solution of isopropanol and distilled water under stirring at room temperature; adding NaOH aqueous solution up to the alkalization of the mixture; adding monochloroacetic acid in isopropanol; filtrating; suspending in methanol solution and neutralizing with acetic acid. The CMC obtained from the process can be employed in a several industrial processes.