Photographic images of axisymmetric diffusion flames were interpreted using the computed tomographic technique. The two dimensional images of an axisymmetric diffusion flame were measured by a commercial CCD array camera and a frame grabber. The image data were then used to reconstruct the original three dimensional spatially resolved distributions of emission intensities by using the computed tomographic technique. The reconstructed volumetric emission intensities were then converted into optical temperatures of soot particles by assuming that the system response parameters were constant. The constants were determined from the calibration tests with a blackbody cavity, along with thermocouple measurements. The reconstructed temperatures, which were considered as the temperatures of soot particles, showed reasonable resemblance to the expected temperature distribution. The characteristics of the optical system, such as F number and pixel distance (magnification of image), with respect to the accuracy of reconstructed data were discussed.