Hydrogen/oxygen　fuel　cells　were　successfully　utilized　in　the　field　of　space　applications　to　provide　electric　energy　and　potable　water　in　human-rated　space　mission　since　the　1960s.　Proton　exchange　membrane　(PEM)　based　fuel　cells,　which　provide　high　power/energy　densities,　were　reconsidered　as　a　promising　space　power　equipment　for　future　space　exploration.　PEM-based　water　electrolyzers　were　employed　to　provide　life　support　for　crews　or　as　major　components　of　regenerative　fuel　cells　for　energy　storage.　Gas/water　and　heat　are　some　of　the　key　challenges　in　PEM-based　fuel　cells　and　electrolytic　cells,　especially　when　applied　to　space　scenarios.　In　the　past　decades,　efforts　related　to　gas/water　and　thermal　control　have　been　reported　to　effectively　improve　cell　performance,　stability　lifespan,　and　reduce　mass,　volume　and　costs　of　those　space　cell　systems.　This　study　aimed　to　present　a　primary　review　of　research　on　gas/water　and　waste　thermal　management　for　PEM-based　electrochemical　cell　systems　applied　to　future　space　explorations.　In　the　fuel　cell　system,　technologies　related　to　reactant　supplement,　gas　humidification,　water　removal　and　active/passive　water　separation　were　summarized　in　detail.　Experimental　studies　were　discussed　to　provide　a　direct　understanding　of　the　effect　of　the　gas-liquid　two-phase　flow　on　product　removal　and　mass　transfer　for　PEM-based　fuel　cell　operating　in　a　short-term　microgravity　environment.　In　the　electrolyzer　system,　several　active　and　static　passive　phaseseparation　methods　based　on　diverse　water　supplement　approaches　were　discussed.　A　summary　of　two　advanced　passive　thermal　management　approaches,　which　are　available　for　various　sizes　of　space　cell　stacks,　was　specifically　provided