The thermolysis of three bis(tert-alkylperoxy)alkanes and two 1,1-bis(tert-alkylperoxy)cycloalkanes was undertaken at various temperatures between 333 and 383 K and the radicals generated trapped employing DMPO, DEPMPO, PBN-d14 and TTBNB. The appropriate tert-alkoxyl radical was trapped during the thermolysis of all five peroxides and underwent -scission to give the appropriate alkyl radical and ketone. Although the appropriate sister O-centred 1-(tert-alkylperoxy)alkoxyl radicals (3) were not trapped, adducts of the radicals derived from them via -scission were observed. The ethyl radical was trapped during the thermolysis of 2,2-bis(tert-butylperoxy)butane (1a) and the ethoxycarbonylmethyl radical during the thermolysis of both ethyl-3,3-bis(tert-butylperoxy)butyrate (1b) and ethyl 3,3-bis(tert-amylperoxy)butyrate (1c), thus establishing the thermolysis scheme for these bis(tert-alkylperoxy)alkanes. In the case of 1,1-bis(tert-butylperoxy)cyclohexane (2a) it has been established that the sister O-centred [1-(tert-butylperoxy)cyclohexyl]oxyl radical (6a) undergoes a rapid ring-opening reaction to give the 5-(tert-butylperoxycarbonyl)pentyl radical (7a).