On photoexcitation at 193 nm, the 1(∏,∏*) excited acetaldoxime (CH3-CH=N-OH) appears to be undergoing intersystem crossing producing a highly energized triplet state, which is followed by parallel processes of the emission of a UV photon at 310 nm and the dissociation to CH3-CH=N and OH radicals as primary products.While the laser-induced fluorescence showed that only 1.5% of the nascent OH (X2∏) is produced in the vibrationally excited state with V=1, there is no OH produced with V=2. The rotational state distribution of OH is found to fit a Boltzmann distribution, characterized by a rotational temperature Trot of 1200±120K for the V=0 and Trot of 990±100 K for the V=1 vibrational states, respectively. By measuring the Doppler spectroscopy of the V= 0 and V=1 states of OH, the translational energy of the photofragments is found to be 40.0±5.0 and 2.2±4.0 kcal mol-1, respectively. While 20 kcal mol-1of translational energy is expected statistically, imparting such a large amount of translational energy into the products sug-gests that the dissociation occurs on the excited state potential energy surface. The real time formation of OH shows a dissociation rate of the acetaldoxime to be (1.5±0.3)×106s-1. The above dissociation rate vis-a`-vis statistical Rice-Ramsperger-Kassel-Marcus theory suggests that the acetaldoxime dissociates from the triplet state, with a threshold dissociation energy of about 49 kcal mol-1. The decay of the triplet acetaldoxime emission at 310 nm with a rate of (1.2±(0.3)×106s-1, similar to that of its dissociation to form OH, further suggests that both the competitive decay processes occur from the triplet state potential energy surface.