Laser flash photolysis of benzil in the presence of various amines was investigated to determine absolute reaction quantum yield (phi(r),) of benzil ketyl radicals produced from both free tripler benzil and ground state complex. The reaction quantum yields of benzil ketyl radical from free triplet benzil (phi(r)(free)) were 0.31, 0.17, 0.13, 0.08, and ca. 0 for triethylamine (TEA), N,N-diethylaniline, diethylamine, N-ethylaniline, and aniline, respectively. phi(r)(free) largely depends on the number of the hydrogen atoms that can be abstracted by benzil. The reaction quantum yield of the complex formed in the ground state (phi(r)(com)) was determined to be unity for all amines used. This large quantum yield (phi(r)(com) = 1) was explained by a calculated conformation of the ground state complex.