A stackable unitized fuel cell system includes a cooling capability. A unitized fuel cell system includes a unitized fuel cell assembly having a first flow field plate, a second flow field plate, and a membrane electrode assembly (MEA) provided between the first and second flow field plates. In one configuration, a cooling structure is separable with respect to the unitized fuel cell assembly. In another configuration, the cooling structure is integral to the unitized fuel cell assembly. A retention arrangement is provided on one or both of the unitized fuel cell assembly and cooling structure. The retention arrangement is configured to facilitate mating engagement between the unitized fuel cell assembly, the cooling structure, and adjacent unitized fuel cell systems of a fuel cell stack.