Several resonance-stabilized radicals are observed as products of an electrical discharge containing p-cymene, a biogenic monoterpene that contributes to secondary organic aerosols after atmospheric oxidation. Three radicals are identified by resonant 2-color 2-photon ionization mass spectrometry, corresponding to loss of a methyl group or hydrogen atom from the parent p-cymene structure. The radicals are found to absorb in the spectral region consistent with a benzylic chromophore. The spectrum observed on m/z 119 is assigned to alpha,4-dimethylbenzyl radical, and those on m/z 133 to the alpha,alpha,4-trimethylbenzyl and p-isopropylbenzyl radicals, the latter two being intermediates in the atmospheric oxidation of p-cymene. (C) 2014 Elsevier B.V. All rights reserved.