A silicon micropacked-bed reactor for phosgene synthesis is demonstrated as an example of the potential for safe on-site/on-demand production of a hazardous compound. Complete conversion of chlorine is observed for both a 2:1 CO/Cl2 feed at 4.5 std. cm3/min and a 1:1 feed at 8 std. cm3/min. The latter gives a projected productivity of ∼100 kg/yr from a 10-channel microreactor, with the opportunity to produce significant quantities through operating many reactors in parallel. The versatility of silicon microfabrication technology for producing reactors for corrosive gases is demonstrated by a protective oxide coating formed during reactor fabrication. The increased heat and mass transfer inherent at the submillimeter reactor length scale provides a larger degree of safety, control, and suppression of gradients than is available in macroscale systems. These advantages are also explored in the extraction of chemical kinetics from microreactor experiments. The preexponential factor and apparent activation energy for phosgene formation are determined demonstrating the utility of micropacked-bed reactors as laboratory research tools.