Participates in fatty acid beta-oxidation (FAO) and energy production in the central nervous system (CNS), and to a lesser extent in the liver (PubMed:21237683). Catalyzes the first step in FAO, which consists in the proR-proR stereospecific alpha,beta-dehydrogenation of fatty acyl-CoA thioesters using the electron transfer flavoprotein (ETF) as their physiologic electron acceptor, with maximal activity towards saturated docosanoyl-CoA (CoA 22:0) in both the cerebellum and the liver (PubMed:21237683). Among the different mitochondrial acyl-CoA dehydrogenases, its FAO activity overlaps with that of ACADV and ACADL, but plays a primary role in tissues where it is the main long-chain ACAD expressed, such as the CNS, where together with ACAD9, they accommodate the full spectrum of long chain fatty acid substrates (PubMed:21237683). . This is the function of ACAD11 (acyl-CoA dehydrogenase family member 11, Ensembl gene identifier ENSG00000240303).