The photon-driven chemistry of biacetyl (CH3COCOCH3) on Ag(111) has been studied using temperature-programmed desorption, Auger electron spectroscopy, and time-of-flight mass spectrometry. Irradiation of both monolayer and multilayer biacetyl with 193 nm photons results in the prompt ejection of CH3 radicals that exhibit bimodal translational temperatures of 2700 +/- 100 and 290 +/- 20 K. Irradiation of multilayer biacetyl with 193 nm also leads to ejection of CO with translational temperatures of 1170 +/- 40 and 140 +/- 10 K, ketene (CH2CO) with translational temperatures of 1000 +/- 60 K, and acetyl-containing fragments with translational temperatures of 320 +/- 20 K. Indicative of the ejection of all reaction products from the surface during irradiation, postirradiation TPD shows loss of parent only, and C-(a) and O-(a) are absent from the surface after irradiation and subsequent heating to 700 K. The cross section for total loss of 1 ML biacetyl is 2.0 +/- 0.3 x 10(-21) cm(+2) at 193 nm. Studies using 248 nm radiation, as well as radiation from a Hg are lamp, were also undertaken.