The quantum yields for O(D-1) production in O-3 photolysis between 203 and 320 K, and 289 to 329 nm were measured. A portion of the observed O(D-1) quantum yields at wavelengths greater than 310 nm is attributed to a spin-forbidden channel and the variation of quantum yield with temperature is ascribed to photodissociation of vibrationally (or rotationally) excited ozone. Our results yield atmospheric O(D-1) production rates larger than those obtained from current recommendations, especially at high solar zenith angles, low temperatures, and large overhead ozone columns.