Abstract: Presented are passive-type separator assemblies for separating hydrogen and water in fuel cell systems (FCS), methods for making/using such separators, and FCS-powered vehicles equipped with such separators. A liquid-gas separator assembly for an FCS includes an outer housing with an internal compartment, a first port fluidly connecting this internal compartment to an FCS transfer conduit to receive FCS exhaust, and a second port fluidly connecting the internal compartment to an FCS exhaust manifold to transfer water separated from the exhaust. A third port fluidly connects the internal compartment to an FCS hydrogen inlet to transfer hydrogen extracted from the exhaust. A first chamber located inside the internal compartment fluidly connects the first and second ports and evacuates extracted water from the compartment. A second chamber located inside the internal compartment above the first chamber fluidly connects the first chamber to the third port and evacuates extracted hydrogen from the compartment.