The double carbonylation of benzyl chloride to phenylpyruvic acid (PPA) catalyzed by CoCl2.6H(2)O and potassium pyridine-2-carboxylate (KPyca) in Ca(OH)(2)/dioxane/H2O system has been studied. The effects of ligands, concentration of catalysts, solvents, temperature, CO pressure and the molar ratio of Ca(OH)(2)/PhCH2Cl on the conversion and selectivity have been investigated. The conversion of benzyl chloride was 71.3%, and the yield of PPA was 70.1% with selectivity 98.3% when the reaction was carried out for 10 h at 353 K and 2.8 MPa of CO in the Ca(OH)(2)/dioxane/H2O system, with CoCl2 0.035 mol/l, KPyca 0.13 mol/l, and the ratio of Ca(OH)(2)/PhCH2Cl 2.0. The product PPA was characterized by IR, H-1 NMR, MS and UV. The mechanism of this catalytic reaction has also been discussed. (C) 2002 Elsevier Science B.V. All rights reserved.