The nanosecond laser flash photolysis (time resolution 3 ns) has been used to study the primary processes in photochromic reaction of three O-acylic derivatives of 1-oxy-2-methoxyanthraquinone with methyl (I), ethoxyl (II) and diethylamino (III) in migrating acyl. The triplet-triplet absorption spectra of the reactive triplet states of quinones II and III were detected. The triplet and ground states absorption spectra of the photoproduct (ana-quinone) were observed; the quantum yields of ana-quinone formation and the rate constants of all elementary steps were measured in toluene at room temperature. It was confirmed in the present work that photochemical migration of acyl groups is an adiabatic process occurring on the triplet potential energy surface.