Cetane is a term used in the context of diesel fuel quality.Cetane is the common name for the alkane molecule hexadecane (C₁₆H₃₄). It is used as a reference standard with a high cetane number (defined as 100) to evaluate the ignition quality of diesel fuel.The cetane number is a measure of a diesel fuel’s autoignition delay time. Fuels with higher cetane numbers ignite more readily under compression, leading to smoother engine operation.