A method and catalyst system for producing aromatic carbonates from aromatic hydroxy compounds. In one embodiment, the method includes the step of contacting at least one aromatic hydroxy compound with oxygen and carbon monoxide in the presence of a carbonylation catalyst system having catalytic amounts of the following components: a Group VIII B metal source; a combination of inorganic co-catalysts including a copper source and at least one of a titanium source or a zirconium source; an onium chloride composition; and a base. Alternative embodiments include inorganic co-catalyst combinations of a lead source and at least one of a titanium source or a manganese source.