Acyl CoA is oxidised to Enoyl CoA by Acyl CoA dehydrogenase.
Enoyl CoA is hydrated and H2O is split into H and OH and form hydroxyacyl CoA by Enoyl CoA Hydratase.
Hydroxyacyl CoA is oxidised to form 3-Ketoacyl CoA by hydroxyacyl CoA dehydrogenase.
Thiol group of CoA-SH attacks the beta-gamma carbon bonds of 3-Ketoacyl CoA liberating 2 carbons which bind to CoA and form Acetyl CoA.