An inexpensive, low-power quartz capillary flow reactor was designed to investigate the global reaction rare for the supercritical water oxidation. of acetic acid. The effluent from the similar to 0.1 cm dia. quartz microreactor is such that it is easily incorporated into an online spectroscopic or vacuum mass spectrometer detection system. The reactor is capable of operating up to 28 MPa and 530 degreesC. Standard HPLC sample; injection valves permit the rapid change of reactant composition. This reactor is a nonisothermal design and requires a heat-transfer calculation that involves coupling the transport equations for momentum, mass, and heat with the chemical kinetics equations. A numerical calculation presented includes a rigorous treatment of the equation of state and the trans' port properties of pure water. With this design, the global rate data was fitted to the following form: r(A) = - 9.3 +/- 0.7 X 10(10)e(-(172.2 +/- 1.7)/RT) [C-HOAc](0.89 +/- 0.07) [C-Peroxide](0.2 +/- 0.1)(M/s).