This paper presents an application of the reaction class transition state theory (RC-TST) for prediction of thermal rate constants of the O(P-3) + alkane -> OH + alkyl reaction class. Parameters of the RC-TST were derived from first principles from a set of 19 reactions representing hydrogen abstractions from primary, secondary, and tertiary carbon atoms so that rate constants of any reaction in this class can be estimated without any further information or with its reaction energy calculated either at the density functional theory BH&HLYP/cc-pVDZ level or the semiempirical AMI level. Detailed error analyses show that when compared to explicit theoretical calculations, the systematic errors in the calculated rate constants arising from the use of analytical expressions to approximate different reaction class factors in the RC-TST method are less than 40% on the average over the temperature range from 300 to 3000 K. In addition, we found that the rate constants estimated using either approach are in good agreement with available data in the literature. (c) 2007 The Combustion Institute. Published by Elsevier Inc. All rights reserved.