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=[Ph 2 NNC(CH 3 )CSRSR] and R=CH 3 , CH 2 CH 2 and X=Cl, CCPh, CCSi(CH 3 ) 3 . These catalytic systems show high catalytic activity in ethylene polymerization, especially when the reactions were carried out at a temperature of 80°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.