The catalytic activity of the [PdCl2(dppp)] complex in the 1-olefin/ethene (E)/CO terpolymerisation has been studied in MeOH (containing 1000ppm of H2O) as a solvent. The 1-olefins tested were propene (P), 1-hexene (Hex), 1-decene (D) and styrene (S). At 90 degrees C and 45 atm (E/CO=1/1). the system [PdCl2(dppp)]/TsOH (p-toluenesulfonic acid)=1/8 catalyses efficiently the reactions leading to 5000 g PECO/(g Pd h), 5600 g Hex ECO/(g P dh), 5650 g DECO/(g Pd h) and 4100 g SECO/(g Pd h). In particular. it has been Studied deeper the effect of Hex and S concentrations on productivities. average molecular weights and melting temperatures of HexECO and SECO, respectively. A mechanism of reaction has been also proposed and discussed, Supported by IR, and NMR characterizations. (C) 2008 Elsevier B.V. All rights reserved.