ThO2-PuO2 mixed oxide (MOX) experimental fuel pins have been fabricated at Bhabha Atomic Research Centre, for irradiation experiments as a part of an advanced fuel development programme. During the quality control of fuel pellets, the homogeneous distribution of the fissile plutonium in them has been ascertained using alpha autoradiography and gamma autoradiography techniques. The quantitative estimation of the plutonium-rich regions of the pellets has been carried Out by optical microdensitometry and digital image analysis. This paper discusses the implementation of the techniques and presents a few typical results. (C) 2003 Elsevier Ltd. All rights reserved.