Chitin, chitosan and modified chitosan, biopolymers which have structures similar to that of cellulose, are proposed for removal of copper ion from diesel oil. These natural polymers had been used before for recovering traces of metals from aqueous solutions and from industrial and sea waters. The present work describes the obtention and characterisation of chitin, chitosan and modified chitosan polymers. The removing ability of these polymers for copper ion has been demonstrated in diesel oil and chitosan presented the best performance. The removal percentage from kinetic studies depends on several factors as the polymer type, the temperature and the contact time and reaches values of about 92% at equilibrium.