A novel oscillating system with no dark oscillations, possessing a single photochemical autocatalytic feedback loop triggered by VW photolysis of ozone, is proposed. This gas phase photochemical oscillator is extremely simple, involving. only ozone, triplet oxygen radical, molecular oxygen, and one additional species, which provides the necessary destabilizing exit reaction. The phase diagram for the suggested system is constructed, and experimentally realistic values of rate constants and light intensity corresponding to the oscillatory regime are found.