A zero-dimensional single-zone combustion and an availability balance model for low temperature combustion (LTC) engines have been developed combined with skeleton mechanism of primary reference fuel and the first and second law of thermodynamics. The variation of system availability is analyzed, and the effects of nine major species (OH, CH2O, H2O2, C3H6, C8H18, C7H16, CO, CO2, H2O) on availability conversion are studied. The influences of fuel octane number on the availability of LTC process are studied to investigate the effects of fuel characteristics on availability destruction of HCCI combustion process. The irreversibility increases and heat transfer availability decreases with the rise of iso-octane volume fraction in primary reference fuels (PRFs). (C) 2014 Elsevier Ltd. All rights reserved.