Exploring the vast space has always been one of the greatest dream for all humanbeings. The International Space Station (ISS) is currently working as a test platform forexperimenting various essential equipment for further deep-space exploration andcolonization. Because of limited space for storing water on ISS, Water Recovery System(WRS) is heavily depended to produce recycled drinkable water from collected wastewater.As one important component of WRS, the thermal catalytic reactor is designated to removeall Volatile Organic Compounds (VOCs) which is difficult to be dissolved by othertreatments. However, the high temperature and pressure working environment makes someof its fragile parts need continuous replacements leading to increased cost and potentialrisks.Herein, we propose a photocatalytic microfluidic reactor (PMFR) which can beoperated at normal temperature and pressure to replace the thermal catalytic reactor. Forthis titanium (Ti) PMFR, micropillar arrays covered with nanoporous titania (NPT) aredesigned to attain increased surface area to volume ratios, reduced diffusion lengths, andgreater uniformity of irradiation. For the first time, the microelectromechanical systemsviii(MEMS) techniques are used to fabricate a Ti-based microfluidic reactor.For the first degradation study with organic dye Methylene Blue, the micropillarreactor (MP) was found to dramatically outperform its planar counterpart and the 50 μmdeep MP (MP50) presented at least two times higher degradation activity than otherreported PMFRs. The second study introduced a VOC half-life estimation model designedbased on the steady-state concentration of hydroxyl radicals (·OH). This radical wasconsidered as the main reactant of the photocatalytic degradation of VOCs, and itsconcentration was measured by using nitrobenzene as probe. Half-lives for all VOCsexisted in the Ersatz wastewater proposed by NASA were estimated, and results indicatedthat the MP50 was capable of dissolving most of these VOCs at or under around 100seconds. The third and last study looked into the MP50 degradation performance with twocommon stubborn VOCs – ethanol and 1,4-dioxane. Results showed that MP50 eventuallyfully mineralized about 11.78% of ethanol. As for 1,4-dioxane, MP50 successfullydegraded around 78.83% of it with a reaction rate constant two to three orders of magnitudehigher than that of other bulk reactors reported in literatures. These findings demonstrate agreat potential for the micropillar PMFR to replace thermal catalytic reactor on ISS andeven be used for more varieties of water purifications.