An optical system formed by four point-diffraction interferometers is used for measuring the temperature distribution of a candle flame. It is assumed that the phase can be expressed in terms of the Radon transform, and it is processed with a tomographic iterative algorithm to obtain the temperatures. The interferograms show the asymmetry of the candle flame, justifying the use of a tomographic iterative algorithm instead of the Abel inversion. The resulting temperature distribution verifies the usefulness of the proposed method. © 2013 Society of Photo-Optical Instrumentation Engineers (SPIE) [DOI: 10.1117/1.OE.52.10.104103]