Catalyzes the final step of fatty acid oxidation in which acetyl-CoA is released and the CoA ester of a fatty acid two carbons shorter is formed. acetyl-CoA + an acyl-CoA = a 3-oxoacyl-CoA + CoA Lipid metabolism; fatty acid beta-oxidation. Heterotetramer of two alpha chains (FadB) and two beta chains (FadA). Belongs to the thiolase-like superfamily. Thiolase family.