Rate coefficients of β-scission reactions in tertiary alkoxy radicals, R(CH3)2CO (R = methyl, ethyl, tert-butyl and neo-pentyl) have been estimated via density functional theory (DFT) calculations in conjunction with statistical unimolecular rate theory. For tert-butoxy, results obtained by employing different basis sets are compared with experimental values, indicating that UB3LYP/6-31G(d,p) excellently predicts kinetic data. Rate coefficients for inter- and intramolecular hydrogen abstraction are also reported. Depending on R, the β-scission rate may vary by orders of magnitude. The predicted temperature dependence of the alcohol-to-ketone product ratios for alkoxy radical decomposition in a hydrocarbon environment is in remarkably close agreement with the corresponding ratios measured on the product mixtures from decomposition of tert-butyl and tert-amyl peroxyacetates in solution of n-heptane.