X-ray small angle scattering from flames has been reported for the first time. A butadiene/air slot burner and a liquid-fuelled wick burner have been studied using a synchrotron radiation source and exposures of less than 15 minutes. Data analysis assumed the presence of a distribution of spherical soot particle diameters; the following most probable diameters were obtained: butadiene/air slot burner 210 Ȧ allyl alcohol wick burner, 250 Ȧ Diesel-fuelled wick burner, 310 Ȧ. Possible improvements to the technique, its relation to optical Mie scattering, and future directions are also discussed