The heat resistance and the structural integrity of syntactic foam materials are vital for their high performance. Syntactic foam made of hollow glass microspheres and Diglycidyl Ether of Bisphenol A (DGEBA) based epoxy resin cured with Isophorone Diamine (IPD) hardener was subjected to oxidative thermal stress cycles. The degraded syntactic foam sample was examined using an X-ray Micro Computed Tomography (XμCT) to evaluate its internal damage between each state in a combined effect of cycling and increased temperature. Glass microsphere fracture, void enlargement and resin microcracks were observed as a result of the thermal stress using 3D XμCT images. The reconstructed slice representation showed the microcracks and microsphere damage distribution inside the sample. The damaged glass spheres percentage is shown to increase sharply with the progress of the thermal cycle. There was no change in the local density of the syntactic foam as a result of the thermal cycle. An XμCT system proves to be a successful non-destructive technique for examining syntactic foam for defects and structural damages in the micron scale.