1,4-Benzoquinone is uncovered to react with acidic bromate in the presence of illumination, in which temporal oscillations are observed in the stirred batch system. This new photochemical oscillator shows subtle dependence on compositions of the reaction mixture, in which oscillations could be revived immediately upon the addition of fresh 1,4-benzoquinone solution. A proposed mechanism on the basis of light-induced conversion of 1,4-benzoquinone to 1,4-hydroquinone qualitatively reproduces the oscillatory phenomena as well as the long induction time seen in experiments. (c) 2006 Elsevier B.V. All rights reserved.