This paper focuses on 3-dimensional non-destructive characterization of the morphologies of integral-skin cellular polymeric composites using X-ray Microtomography. Rapid Rotational Foam Molding (RRFM) is a polymer processing technology that is capable of creating composites with intricate shapes that have a foamed core surrounded by an integral solid skin layer (similar to the structure of a bone). The analyzed specimens were extracted from composites processed in RRFM having a solid skin made of polypropylene (PP) grades combined with foamed cores made of both polyethylene (PE) and PP grades by implementing a suitable chemical blowing agent (CBA) in extrusion. The resulting cellular structures pertaining to the foamed core and the near-skin area were visualized and their morphological quality was evaluated in terms of cell size distribution and cell density. The stress-strain behavior and 3-dimensional structural changes were monitored and characterized with in-situ compression testing.