The CIDEP of transient alkyl radicals, generated by triplet sensitization of symmetrical azoalkanes, is studied by time-resolved EPR (TREPR) spectroscopy. The polarization is found to consist of two net components, one reflecting the polarization of the triplet sensitizer, and the other being attributable to a reversed triplet mechanism taking place in the triplet sensitized azo compound. The latter amounts to - 8.4 +/- 1.5 times the Boltzmann polarization for triplet sensitized AIBN at room temperature in benzene. For the benzophenone/AIBN system it is found that spin relaxation in triplet benzophenone and quenching by AIBN occurs with T-3(1) = (6.4 +/- 1.3) ns and k(q)(T) = (9:3 +/- 0.2) X 10(8) M-1 s(-1) under these conditions.