High temperature experiments were performed with the reflected shock tube technique using multi-pass absorption spectrometric detection of OH radicals at 308 nm. The present experiments span a wide T-range, 801-1347 K, and represent the first direct measurements of the title rate constants at T > 500 K for cyclopentane and cyclohexane and the only high temperature measurements for the corresponding methyl derivatives. The present work utilized 48 optical passes corresponding to a total path length similar to 4.2 m. As a result of this increased path length, the high [OH] detection sensitivity permitted unambiguous analyses for measuring the title rate constants. The experimental rate constants in units, cm(3) molecule(-1) s(-1), can be expressed in Arrhenius form as k(OH+Cyclopentane) = (1.90 +/- 0.30) x 10(-10) exp(-1705 +/- 156 K/T) (813-1341 K), k(OH+Cyclohexane) = (1.86 +/- 0.24) x 10(-10) exp(-1513 +/- 123 K/T) (801-1347 K), k(OH+Methylcydopentane) = (2.02 +/- 0.19) x 10(-10) exp(-1799 +/- 96 K/T) (859-1344 K), k(OH+Methylcyclohexane) = (2.55 +/- 0.30) x 10(-10) exp(-1824 +/- 114 K/T) (836-1273 K). These results and lower-T experimental data were used to obtain three parameter evaluations of the experimental rate constants for the title reactions over an even wider T-range. These experimental three parameter fits to the rate constants in units, cm(3) molecule(-1) s(-1), are k(OH+Cyclopentane) = 1.390 x 10(-16)T(1.779) exp(97 K/T) cm(3) molecule(-1) s(-1) (209-1341 K), k(OH+Cyclohexane) = 3.169 x 10(-16)T(1.679)exp(119 K/T) cm(3) molecule(-1) s(-1) (225-1347 K), k(OH+Methylcyclopentane) = 6.903 x 10(-18)T(2.148) exp (536 K/T) cm(3) molecule(-1) s(-1) (296-1344 K), k(OH+Methylcyclohexane) = 2.341 x 10(-18)T(2.325) exp(602 K/T) cm(3) molecule(-1) s(-1) (296-1273 K). High level electronic structure methods were used to characterize the first three reactions in order to provide reliable extrapolations of the rate constants from 250-2000 K. The results of the theoretical predictions for OH + cyclohexane and OH + methylcyclopentane were sufficient to make a theoretical prediction for OH + methylcyclohexane. The present recommended rate expressions for OH with cyclohexane, and methylcyclohexane, give rate constants that are 15-25% higher (over the T-range 800-1300 K) than the rate constants utilized in recent modeling efforts aimed at addressing the oxidation of cyclohexane and m ethyl cyclo hexa ne. The current measurements reduce the uncertainties in rate constants for the primary cycloalkane consumption channel in a high temperature oxidation environment. (C) 2008 The Combustion Institute. Published by Elsevier Inc. All rights reserved.