A new catalytic process for preparing acetic acid may offer advantages in cost, selectivity, and safety compared with today's industrial methods for manufacturing the commodity chemical. Current large-scale methods for producing acetic acid rely on solution-phase complexes of rhodium or iridium to catalyze the reaction of methanol with carbon monoxide in the presence of methyl iodide catalyst promoters. Now, a team led by Enrique Iglesia at the University of California, Berkeley, reports that carbonylation of dimethyl ether to methyl acetate (which can be hydrolyzed to yield acetic acid) can be carried out with nearly 100% selectivity, using acidic zeolite catalysts (Angew. Chem. Int. Ed., published online Jan. 30, dx.doi.org/10.1002/anie.200503898). The new method, which proceeds under mild reaction conditions (100-150 °C), makes use of stable and easily recovered solid-phase catalysts and sidesteps the need for toxic and corrosive halide compounds.