This paper describes catalytic applications of new orthopalladated complex/MAO systems in polymerization of ethylene and copolymerization of ethylene/10-undecen-1-ol. Orthopalladated complexes 1-5 were synthesized from tridentate ligands [C, N, S], with a general formula of PdLX, where L [Ph2NN=C(CH3)-C=SRSR] and R = CH3, -CH2CH2- and X = Cl, -C CPh, -C CSi(CH3)(3). These catalytic systems show high catalytic activity in ethylene polymerization, especially when the reactions were carried out at a temperature of 80 degrees C. The polyethylene obtained is linear with narrow molecular weight distributions, indicating that Pd/Al systems behave as single site catalysts. The results obtained in copolymerization of ethylene/10-undecen-1-ol indicate that orthopalladated complex/MAO system produces copolymers with molecular weight distributions unimodal and close to 2, indicating that the Pd/Al systems also act as single site catalysts. (C) 2011 Elsevier B.V. All rights reserved.