Environmental control systems for manned exploration spacecraft and lunar/planetary bases will need a condensing heat exchanger (CHX) to control humidity in crew habitat modules. Antimicrobial coatings are needed to prevent growth of microbes and formation of biofilms on the condensing surfaces inside the CHX and maintain a healthy spacecraft environment. Creare has developed a highly adherent, hydrophilic, antimicrobial coating that can be applied to heat exchanger surfaces. However, recent studies have shown that the lifetime of this coating may be limited in prototypical environments. We propose to develop an improved coating process that builds on our prior coating development but adds features to extend the lifetime, potentially to ten years. In Phase I we will prove the feasibility of our approach through theoretical studies of coating stability, deposition of trial coatings, analysis of the coatings, and measurement of coating performance after exposure to prototypical environments. In Phase II we will scale up and refine the process, produce prototypical CHX cores with the hydrophilic and antimicrobial coating, and demonstrate performance after extended exposure to prototypical environments.