Foamed and solid polycarbonate/carbon nanotube (PC/CNTs) composites containing various CNTs contents (0.5 wt.%) were prepared by melt blending.Foamed composites were achieved using dissolved carbon dioxide.The morphology, properties of the nanocomposites and the nucleation efficiency of CNTs in foaming PC were discussed.The results indicate that the cell size decreases and the cell morphology is improved with the help of the CNTs.