A total of 400 trajectories for the photodissociation, CH3CHO --> CH3 + HCO, on the T-1 potential surface have been calculated using the direct ab initio molecular dynamics method at the UB3LYP/cc-pVDZ level of theory. It was predicted that the product CH3 is neither vibrationally nor rotationally excited and HCO is vibrationally not excited but rotationally excited. The averaged HCO rotational energy was calculated to be 1.1 kcal mol(-1), which is 15.1% of the available energy, 7.3 kcal mol(-1). The present result agrees with experiment within just a few percent of the observed data. (C) 2003 Elsevier Science B.V. All rights reserved.