Topological insulators (TIs) are a new quantum state of matter which have bulk insulation but topologically protected metallic surface states. Initially, the TI state was thought to only exist in band insulators but it was found that Kondo insulators, which are correlated electron systems, could also be TIs. One promising topological Kondo insulator (TKI) candidate is the rare earth compound YbB6. The most compelling evidence is angle-resolved photoemission spectroscopy data which indicate YbB6 has topologically non-trivial surface states. SmB6, the most well-known TKI candidate, has recently been studied using time-of-flight (TOF) neutron scattering and the data showed a band structure which satisfy the TI conditions. We propose to investigate the hybridization gap of YbB6 using the inelastic neutron TOF technique with the purpose of discovering any new features related to its TI nature