A fuel cell stack having a plurality of connected modules. Each module includes an elongate hollow member and at least one passage extending through the hollow member. Each hollow member has a first flat surface and a second flat surface arranged parallel to the first flat surface. A first module includes a plurality of fuel cells arranged on at least one of the first and second flat surfaces. A first end of each module has an integral spacer and the modules are connected by the spacer of a first module contacting a second end of a second module.