Organic hydroperoxides have atmospheric roles in secondary organic aerosol formation and maintaining OH radical concentrations. Monitoring OH from CH3CH2OOH and (CH3)(3)COOH at 266, 291, 331, 362, and 377 nm yields trends in energy disposal and absorption cross sections. Nascent OH radicals emerge similarly, but with less translational energy from the heavier parent. Cross sections are new for CH3CH2OOH and extend the range for (CH3)(3)COOH, which has implications for modeling atmospheric OH concentrations. Lower cross sections and higher OH rotation for (CH3)(3)COOH <331 nm could be due to a higher trans barrier for torsion about the O-O bond, compared to CH3OOH and CH3CH2OOH. (C) 2013 Elsevier B.V. All rights reserved.