The invention relates to a catalytic system for the copolymerisation of a conjugated diene and at least one mono-olefin, a method for production of said catalytic system, a method for production of a copolymer of a conjugated diene and at least one mono-olefin, using said catalytic system and said copolymer. The catalytic system comprises (i) an organometallic complex, represented by the following generic formula (1) {[P(Cp)(F1)Ln(X)(Lx)}p, where Ln is a lanthanide atom to which is bonded a ligand molecule with cyclopentadienyl (Cp) and fluorenyl (F1) groups, bonded to each other by means of a bridge (P) of formula MR1R2, where M is an element of the IVA group and where R1 and R2, independently = an alkyl group with 1 to 20 C atoms, or cycloalkyl or phenyl groups with 6 to 20 C atoms, where X = a halogen which can be chlorine, fluorine, bromine, or iodine, where L comprises an optional complexing molecule such as an ether and, optionally a substantially less complexing molecule such as toluene, where p is a whole natural number equal to or greater than 1 and x is equal to or greater than 0 and (ii) a co-catalyst belonging to the group of alkyl magnesiums, alkyl lithiums, alkyl aluminiums, Grignard reagents and mixtures of said components.