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Adiabatic self-heating tests were carried out on five New Zealand coal samples ranging in rank from lignite to high-volatile bituminous. Kinetic parameters of oxidation were obtained from the self-heating curves assuming Arrhenius behaviour. The activation energy E (kJ mol -1 ) and the pre-exponential factor A (s -1 ) were determined in the temperature range of 70 -140ºC. The activation energy exhibited a definite rank relationship with a minimum E of 55 kJ mol -1 occurring at a Suggate rank of~6.2 corresponding to subbituminous C. Either side of this rank there was a noticeable increase in the activation energy indicating lower reactivity of the coal. A similar rank trend was also observed in the R 70 self-heating rate index values that were taken from the initial portion of the self-heating curve from 40 to 70ºC. From these results it is clear that the adiabatic method is capable of providing reliable kinetic parameters of coal oxidation.