Impregnation technique is an attractive alternative for manufacturing highly radiotoxic ²³³U bearing thoria based mixed oxide fuel pellets, which are remotely treated in hot cell or shielded glove-box facilities. This technique is being investigated to fabricate the fuel for the forthcoming Indian Advanced Heavy Water Reactor (AHWR). In the impregnation process, porous ThO₂ pellets are prepared in an unshielded facility which are then impregnated with 1.5 molar uranyl nitrate solution in a shielded facility. The resulting composites are dried and denitrated at 500^oC and then sintered in reducing/oxidizing atmosphere to obtain high density (Th,U)O₂ pellets. In this work, the densification behaviour of ThO₂–2% UO₂ and ThO2–4% UO₂ pellets was studied in reducing and oxidizing atmospheres using a high temperature dilatometer. Densification was found to be larger in air than in Ar–8% H₂. The characterization of the sintered pellets was made by optical microscopy, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The grain structure of  ThO₂–2% UO₂ and ThO₂–4% UO₂ pellets was uniform. The EPMA data confirmed that the uranium concentration was slightly higher at the periphery of the pellet than that at the centre.