L-Carnitine hydrochloride ((R)-Carnitine hydrochloride) is a highly polar small zwitterionic molecule that functions as an essential cofactor for mitochondrial β-oxidation. L-Carnitine hydrochloride facilitates the transport of long-chain fatty acyl-CoAs into mitochondria for subsequent degradation via β-oxidation, thereby supporting cellular energy metabolism. L-Carnitine hydrochloride also displays antioxidant activity and can mitigate metabolic imbalances associated with numerous inborn errors of metabolism, positioning it as an important agent in metabolic research.