This study aims to demonstrate radiometric temperature measurement using incoherent digital holography. Since in-focus images of thermal radiations can be reconstructed at any distance, three-dimensional radiometric temperature can be measured. This requires an optical configuration with a fixed magnification to record an incoherent hologram that contains information about the spectral radiance of an object. The derivation of spectral radiance from the intensity signal of a reconstructed image is described, in addition to calibration procedures correlating the holographic signal to radiation temperature. The experimental results and possible sources of uncertainty are discussed.