Alkylidene diesters such as ethylidene diacetate are selectively produced in high yields by reacting an ether and/or an ester under substantially anhydrous conditions with carbon monoxide and hydrogen in contact with a catalyst system comprising a rhodium compound, a halogen component, a palladium cocatalyst and a promoter component which is an agent for liberation of carboxylic acid anions. The process is carried out in the liquid phase in a solvent comprising a carboxylic acid at a temperature in the range of 150.degree. to 190.degree. C. and at a carbon monoxide partial pressure in the range from about 1.0 to 1100 kg/cm.sup.2 and a carbon monoxide/hydrogen mole ratio of 6:1 to 1:2 for the ester reaction and 10:1 to 1:2 for the ether reaction. When ethylidene diacetate is the product, it can then be decomposed to produce vinyl acetate and acetic acid by well-known techniques. Since one mole of acetic acid is also produced in the synthesis of the diacetate, the invention makes possible an overall process for the production of vinyl acetate which produces acetic acid rather than consumes it.