On photoexcitation at 193 nm, the (1)(pi,pi*) 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 (x(2)Pi) is produced in the vibrationally excited state with nu = 1, there is no OH produced with nu = 2. The rotational state distribution of OH is found to fit a Boltzmann distribution, characterized by a rotational temperature T-rot of 1200 +/- 120 K for the nu = 0 and T-rot. of 990 +/- 100 K for the nu = I vibrational states, respectively. By measuring the Doppler spectroscopy of the nu = 0 and nu = 1 states of OH, the translational energy of the photofragments is found to be 40.0 +/- 5.0 and 32.2 +/- 4.0 kcal mol(-1), respectively. While 20 kcal mol(-1) of translational energy is expected statistically, imparting such a large amount of translational energy into the products suggests that the dissociation occurs on the excited state potential energy surface. The real time formation of OH shows a dissociation rate of the ace - taldoxime to be (1.5 +/- 0.3) x 10(6) s(-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) x 10(6) s(-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.