The applicants have used a recent EPSRC award to develop protocols by which INS can be used to investigate methane reforming catalysts. That work is now complete and we have moved on to adapt this heightened technical awareness to examine iron-based Fischer-Tropsch catalysts. A recent allocation of beamtime (RB1210142) produced an unexpected result, namely the presence of a sharp feature in the INS spectrum that we attribute to a magnon response, which appears to reflect the microcrystallinity of a homogeneous distribution of iron oxide particles. This proposal seeks to exploit this novel observation, only observable on certain high specification spectrometers, to determine if this previously unrealized attribute has any correlation with catalytic activity. Thus, the proposal will evaluate the suitability of INS to characterise an important class of iron-based F-T catalyst.