Many bacteria are able to respire using solid minerals and metals as electron acceptors in the absence of oxygen or other diffusible substrates. In Shewanella oneidensis this respiration requires a porin-cytochrome complex that assembles in the outer membrane. This complex is composed of a trans-membrane porin MtrB, a periplasmic deca-haem cytochrome MtrA and a surface exposed outer membrane cytochrome MtrC. We intend to obtain information on the shape and size of the MtrCAB complex, which will inform on the orientation of exposed MtrC as well as whether MtrA either fully or partially enters MtrB, thus providing evidence for MtrB functioning as a sheath for MtrA. We intend to perform small angle neutron scattering experiments using the SANS2D instrument to generate scattering profiles and ultimately a molecular surface model for this membrane protein complex.