The system [PdCl2 (PPh3)(2)]/PPh3/HCl catalyses the carbonylation of ethene in MeOH as a solvent to give methyl propanoate (MP) or a polyketone (PK). The influence of temperature, Pd/P, CO/ethene and Pd/HCl ratios, and concentration of H2O on the catalytic activity has been studied. The catalytic system is active only in the presence of HCl and is stable when P/Pd is >= 6/1 up to 110 degrees C. At 100 degrees C, with Pd/P/HCl = 1/6/1600 (HCl initially added), under 6.0 MPa total pressure, the main product is MP at 1.0 MPa of ethene, whereas is PK when the pressure of the olefin is higher than 4.0 MPa. Water, which forms in the solvent, because of the reaction of MeOH with HCl, has a minor effect. The PK product presents a 2.5-4/1 ratio between the keto and ester end groups. The proposed catalytic cycle takes into account the results. (c) 2007 Elsevier B.V. All rights reserved.