The main goal of the FAMU experiment is to measure for the first time the hyperfine splitting of the muonic hydrogen ground state and, through this measurement, to determine the proton Zemach radius. To achieve this result, it is necessary to characterize first the muon transfer mechanism from muonic hydrogen to oxygen. This study has been carried on by the FAMU Collaboration at the RIKEN-RAL muon facility in the UK. In this work the most recent results on this topic are presented.
